GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION
178
JX A. R. C.-S43 GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION ANNUAL REPORT OF THE NUCLEAR PHYSICS DIVISION Period Ending December 1974 Edited by K. R. P. M. Rao, M. A. Eswaran and D. M. Nadkarni Nuclear Physics Division BHABHA ATOMIC RESEARCH CENTRE BOMBAY. INDIA 1975
-
Upload
khangminh22 -
Category
Documents
-
view
0 -
download
0
Transcript of GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION
JX A. R. C.-S43
GOVERNMENT OF INDIAATOMIC ENERGY COMMISSION
ANNUAL REPORTOF THE
NUCLEAR PHYSICS DIVISION
Period Ending December 1974
Edited by
K. R. P. M. Rao, M. A. Eswaran and D. M. NadkarniNuclear Physics Division
BHABHA ATOMIC RESEARCH CENTRE
BOMBAY. INDIA
1975
B.A.R.C. -843
3 GOVERNMENT OF INDIA• ATOMIC ENERGY COMMISSION
\Sof
ANNUAL REPORTOF THE
NUCLEAR PHYSICS DIVISION
Period Ending December 1974
Edited byK. R. P. M. R*o( M. A. Eawaraa and D. M, Nadkaral
Nuclear Phyaics Divisloa
BHABHA ATOMIC RESEARCH CENTREBOMBAY,
1975
FQBEIitOftO
Thie rsport cavers ths research «nd development activities carried
out in the Division during the calender year 1974. Ouring this pariod
ths Division was reorganised into three major aub unita namely, Van-d*-
Craafr Laboratory, Solid State Physics Section snd F.tsnion Physios section.
The Nuclear Physics programme at the Uan-de-Eraaff Laboratory aialnly
involved resonance reactions and reaction mechanise studies as wall aa
apectroscopic studies utilising electro«agnetic transitions following
reactions induced by protons and alpha particles. Theoretical investigatiom
covered the area of cluster knock—out reactions.
The Fission Physics activities have been mainly directed at the
investigation of the ternary and quaternary fission and towards investiga-
tion of various approaches to shall correction energies for nuclei. The
feature article reviews the situation in the latter field.
In the area of Solid State Physics, the techniques of neutron diff-
raction, neutron inelastic scattering, flosebauar spactroscopy and laser
Raman spectroscopy continued to be utilised for ths investigation of the
properties of magnetic matariaIs and dynamics of condensed madia. Tha
studies of tha momentum distribution cf electrons in polyercryttalllne
material utilising ths Compton scattering of J -rays is a new activity
started during this year.
To carry out active basic research programmes it is necesaery t*
have a relevant development programme in experimental techniques and
instrumentation. Tht success of the Research and Development pregraame of
tha 01vieion has been dus to the progressive building up of tha facilities
of a well equipad Electronic Labaratory and a nechanical Wark-shop, aanna.4
-ii-
by wall trclnad personnel. T* santian a tmm aignif leant, pra>era«a>aa,
Light Scattarlng Spactrotiatara (bath Itaraan and BrJ.ilawlna) with
•Kcallant p«rfori»ing ohar«ctarl*tica( Haavy Ion Soureaa foe tha Variable
Cnarfy Cyclotron, and cartain ao*penanta for tha laotvpa Sapatator ana"
Tandaa Aaaalcrator hawa baan daaignad antj fabricatad. Tha large mmbat
of ltaaa undar that aaetion In this raport rariaeta th» wida intatsat
and aagnituria af thaaa activttlaa In tha Division.
COWTCjjTS
P«Q« WO.
fOfltUORO i
'• fEA7URE ART ICi-CS
1. Thermodynamics of Excited Nuclei and tha
Evaluation of Shall Correction Energies at Nuclei 1
6. HUCLEAR PHYSICS
I. Nmclaar Reactions and Spectroecopie Studies
1. Higher laoopln Ststes in Ar through Alpha
Particle Capture Resonances 19
2. (o(,n) Reactions on Light Nuclei 22
3. Study of 55Mn (p,n)55Fe Reactions Cf
4. Study of (p, V ) Reactions 26
5. Shape Isomar Excitation using 14 WsV Neutron 25
Bombardment
6. Nuclear Spacfcroscopic Studies in the ftaas 75 27
ftagion
7. Spactroacopy of V with (p,n/) Reaction* 28
8» Nuclear Data Measurements 30
9, Spectra of Doubly Odd Nuclei 31
10. Proton Knock-out Reactions, s Proba for tha
Cluster Sizes in Nuclei 34
11• Osutsron Contraction Effects in the d(d,t) p
Reaction 37
12. Oeuteraon Cluster Contraction and tha Quael
Frae Reaction 6Li (d,tp)4Ho 38
13* On the fundamental Representation of SU(3) Croup 39
c, fission PHYSICS1* Uncertainties in tha Shell Correction Energiee
Obtained by the Strutinaky Method for Qeforaad
Nuclear Shapes Relevant to Fission 41
2. Trajectory Calculations in Spontaneous Fission
of 2S2Cf 443. Scission Configuration in Muatsafnary Fission 50
-ill-
P«QO WO,
4. Fission Fragment and Alpha Particle Energy
Correlations in the Thermal Neutron Induced215
Fission of U. 53
SOLID STATE PHYSICS
I . fllButron Diffraction, Studies of WaQnatic Baterlala
1 . Nonspherical Magnetic Moment in DnAlGa 63
2. Polarised Neutron Study of Magnetite 6ti
3. Neutron Diffraction Study of PolycrystsXline
TbAg at 300«K and at 90°K 69
4. A Neutron Diffraction Study of Co-doped YDFGO, 71
II, Neutron Inelastic Scattering and Dynamics of
Condensed Nedla
1 . Librational Modes of Water Flolecules in BeSO 4H,0 73
2. Neutron Inelastic Scattering from (NHL ) SO. and
the Wixed Salts of [ T ^ )x K, 1 2 S04 76
3. Reorientational Motion of Ammonium Ions In
2 ^ 79
4. Ammonium Ion Liisrations in [(NK^ ) K, "1 , CuCl. .
2H20 Mixed Crystals. 81
5. Homogeneous and Hcmeotropic Orientation of Henatica
on Thin Films 35
6. Corapton Scattering of "jf -rays froM Polycryatallino
Titanium 37
7. Stark Ladders in Solids 90
6. On an Isoparimatric Inequality far Energy Level* 90
9. On an Anomalous Property of the Dirac HaaXltenlan
with a Delta-Potential 92
10. On the Correctneea of Slater•• Notation 93
11. Scattering Tensor* for Resonance Rataan Scattering
in Close - Packed Hexagonal Lattice 95
12. Symraet;riz«d Multiple Products of Induced Monomial
Representation 97
Paga Mo.
I I I . Hosabauar Spectra and Hvparflna Flalda
1 . nicto*agnotic Behaviour in Co-1", a Alloya 99
2. Spin Relaxation Effect* in Nicfcal-2inc
Fonitee Using the Motfubauer Effect 100
3. liossbauar Studies of fe^G*. 102
4 . Mosebauar Studies of (Co fa . },. Ge, 103
• EXPERIMENTAL TECHNIQUES A NO INSTRUMENTATION
1 . Isotope Separator 105
2. Van d« Craaff Operation 107
3. Nuclear Detector* Section 107
a. Neutron Radiogrcphy 107
b. Nuclear Detectors 103
4 . a. Ion Implantation 109
b. Instruaant Oavelopnent H6
5. An Insulated Core Transformer Powor Supply
for Ion Implantation 116
6. Determination of Target Thicknasa for Thin
Targets, evaporated on Thick Backings,
Util ising Back-Scattering of Alpha Partialst 120
7. Optimisation of Magnetic Field and R«F. in a
Azimuthally Varying Field Variable Energy
Cyclotron 122
8. Thin Film Sointillator Oatsotor for Fiaslon
Fragments 125
9. Oavalopaant of a *glti-parametar Data Acquialtlon
Syatem 127
10. X—ray 5pectro**try with Si(li) Systeas 128
11. Developnant of a Nondestructive Teeting Tool
Baaed on 'Ooubl* Resonance Hossbauajr Spectroscopy'
("ORtfiUS") rl3C the fleasuranar.t of Residual Surf*c«
Streasaa 152
-vi-
Paoc Wo.
12. Laser Raman Spsctr(Meter 134
13. Fabry Perot Spsct?o»»tar 136
14. Whita Bean Neutron Diffraction 140
15. The Multiplane Analyser 143
16. Frequency Counter 145
17* A Paper Punch-Tape Facility for the 1024 147
Channsl-Analyser
16. Control System for th* flultiarn Triple Axis
Spectrometer 148
19. Large Bismuth Crystals for Incroaead Neutron
Transmission or Low Cnargy Neutrone 149
20. Titaniu* Zirconium Alloy .Capsules to Facilitate
Neutron Scattering Studies at High Pressure* 150
21. Preparation of Alloys and Compounds t51
22. Prograa "Fourer" 152
2 3 . Tandara Accelerator 153
TEACHING AND TRAINING ACTIUITICS i g 5
PUBLICATIONS 1 6 1
NUCLEUft PHYSICS 01WISI0N STAFF 1 6 ?
A. FEATURE ARTICLES
t, Thermodynamics of excited nuclei and the evaluation of shell
correction enargioa of nuclei
Introduction
In the last few years numerous calculations of nuclear deformation
potential energy surfaces have bean carried out based on the now uell-
1 2 3
known macroscopic-microscopic approach, ' ' where the nuclear potential
entrgy as a function of nucleon numbers end deformation is separated into
a smooth part expressible as a liquid-drop maaa formula and a sciii osci-
llating part arising from shell effects. The latter contribution, ktiuun
a* the shell correction energy, is evaluated by considering the independent
particle motion of the nucleons in an appropriate one body potential uelij
as the difference between the sum of energies of the occupied single
particle states and the corresponding quantity of a hypothetical system
with suitably smoothed density of single particle energy states in which
the shell structure has been washed out. In most calculations of nuclear
potential energy surfaces, the smooth system is generated by the uell-
knoun Strutinsky smearing procedure, where each delta function in energy
is replaced by an appropriate smooth function. An alternate approach for
the calculation of the shell correction energy to the nucJear potential
energies has been suggested by us based on a study of ths high temper otuEs-
behaviour of the thermodynamic properties of nuclei. This method basically
exploits the fact that at high temperatures, tha smooth Fermi r<;cupatian
factor of the single particle states in the nuclei makes the influence of
the shell effects on their thermodynamic properties disappear. The general
validity of the method and its basic equivalence to the Strutinsky method
have also been investigated subsequently. In spite of this basic equi-
valence, the following discrepancies have been noticed in tha past. Whil«
-1-
-2-
in most cases, the waluaa of the sliell correction energies aa given by
the Strutinsky method and the temperature ensuring method agree, in
specific instances, disagreement to the extent of 1 fieV or more, haw*g
bean noticed. Detailed investigations have traced the reason for
these discrepancies to the failure of the 5trutinsky method to give rise
to a unique valus of the shell correction energy for those leva! ICJIMSS,
In the first part o* the prusent article, w» present a brief dis-
cussion of ths temperature dependence of shall affects on the therno-
dynamic properties of nuciai, whicl- forma the basis of the temperature
swearing, method of uusluating the shell correction energies. In tha
second part, we give a working recipe for the evaluation of the shell
correction energy, given a aet of single particle energy sigsn vsluas,
followed by typical results obtained for a range of nucleon numbera and
dafarmations.
Statistical properties of excited nuclei
In the recent years, it has baen possible to calculate numerically
the thermodynamic ^uantitiea of nuclei starting fro* shell modai single
particle states and thereby study the influence of nuclear shall afreets
on their thermodynaejic properties as a function of the teaparature of tha
nucleus. The Method of calculation of the important ther«odyna*ie varia-
bles euch as the excitation energy and entropy as a function of the t«ap-
eratjre or the nucleus, given the appropriate sat or shell nodal ringla
particle energy states, is aa followsi
for a system of non-i,it8r«icting faraions, with total nunbar of
porticles N and total energy E, the following relations holdI
s - -
Hera £ are the energisa or the •Ingle particle states and n tm the
Fsrmi-Dlrec distribution function elyan by
whsra T la the thcrnodyneaic taraparaturs and U. is the chemical potential.
For a specified temperature T, the calculation of S and £ can be csxried-
out numerically, on ths baala of eqa.1-4, starting fcom a given eat of
alngla particle energiea € ^ . The corresponding excitation energy £ la
git/en by £ • £ - ^. 6 t e .
On the aeauMption that tha denaity of einyle particle energy leusls
n«cr the Fucsi-lswel la nearly conatant, the above foricallan laada to tha
wall known Batha expreasions
S » 2aT
£ - . T 2
x ••*
whare the parameter •_ is proportional to ths density of 8ingla particle
atates near tne Farml-Xevel. It la now known that in a nucleus, the
danaity of aingle particle statee near the Fermi level ia not conatant
but exhibits appreciable non-uniformitlaa which can ba correlated to tha
wall known shell corrections to thj nuclear potential energies. The taaie
non-uniform distribution of single particle atatsa leada to a deviation
of tha actual entropy and excitation energy froa tha valuea given by tha
Bethu expresaion and these daviations can also be related to ths corres-
ponding shell correction energiea.
Let u- Irst considur the shell correction energy to ths nuclear
potential ; . Let G(£) ~ 7 L $ {&- GyJ be the given, density of single
particle states where G K ara a Bet of shall model aingle partlcja states.
-4-
On the basis or the Strutlnsky-Swiatacki concept, G(6) can be written
aa the aun a smoothly varying part g(6) and a local fluctuation
}^£(«). The shall correction A tto tha total energy is, by da *!,-•. lion
equal to the difference between the ground atate energise of tha actual
eyttem and that of a hypothetical smooth system having a density g(€)
of the single particle states, i.e.,
where C and £ are thu ground etats snergies for the actual and the0 9
corresponding smooth systems, and |J- i* ths Fwrml energy for the smooth
system. Tha smooth single particle level dunsity g{6) correspor..i_ ig to
any lewel achene can be obtained by a suitable smearing of tha snargy
states € , for example,, by ths St.rutinsky smearing procedure.
sJith che above definition of tha ground state shell correction energy,
one can study quantitatively the influence of shell affects on tha ther-
modynamic properties of an excited nucleus. Tor example, a comparison of
the calculated entropy S of the actual system with the corresponding quan-
tity S of the hypothetical smooth tystem evaluated at the same temperature
uili bring out the temperature dependance of ehal. dffacts on entropy.
For thu sake of illustration, we show hers the results of calculations for
ths case of two typi;al schemes of single particle energy states. Tha
first one w»s a model scheme with equidistant levels where each level was
tenfold degenerate. The second one uas modified harmonic oscillator lawel
geoheme. For each of these systems, the corresponding smooth denaity of
etatec was obtained by the Strut insky smearing procedure. The tharmodynamic
quantities S and £ wara calculated from the sat up aqs.1-4, while the
corresponding quantitiaa S and Z for the smooth reference aystem ware obtai-
ned from equations analoguous to aqa.1-4, where Summations are raplacad by
-5-
integretions. Flg.1 shows plots of tha calculated (S»1) and (£-£)
versus the temperature T for tha equidistant Jtsva.1 scheme for the
eaaa of a closed shell and mid-ahsll systems having 1C and 5 particlea
in tha laet Isvsl. rig.2 shows similar plota calculated with the
modified harmonic oscillator level scheme for the cases of the clceed
shall nucleus ,b (spherical shape} and midshell nucleus Pj
(spherics! shape). The following conclusions can b a readily drawn
from flga.1 end 2i
(i) At low temperatures, the actusi system and the laooth syeten<
bshtue differently, as a result of the shell offsets.
{'.I) With increasing tsmperaturo, the differences in tha values of
the total energy and the entropy between thu actual eyetem stici
the referenc* . mooth system dacresee and vanish completely at
high temperatures. A temperature for about 2 ftaV is sufficient
to nearly wipe out the shell effects.
Similar conclusions have basn drawn also by other authors, based
on more extensive calculations covering a wide region of nucleon numbers
and deformations.
On the evaluation of shell corrsction snerolee by temperature
An important consequence of the above high temperature behaviour of
ths thermodynatnic properties of nuclei is as followst In the asymptotic
region of high temperatures, ths entropy S and the total energy Z of the
nucleus become Independent of the local fluctuation tTg(€.) of the single
particle level deneity C(€) snd depend only on (he smoothly varying part
g(*). It has besn shown that this asymptotic behaviour of S and E is
givsn by the rslations
- 6 -
MID SHEU.CLOSED s m i
-as
ai a* o.«t ( Unln ot Iml tpaclpa)
t(M.V)
t l g . 1 i CulculatuU tumpurature Uupundanca of shel l uf fsctt In intropyarid t o t a l uneruy. F ly , la cersr* to • sy»t»m of racmlon* In abuncliud Juuul ucliema, wharu thu lavul t wars aqulipacad and hadu Uuyunuraty of l u . Ins two casu* wtudiuj rafar to th» eloaadsheiJ oyetKii with 1U part iclea in the laat ocuuplad laval andthu »lrt i>h«ll oystMm with S n j r t l c l u i In tha lawt accuplfditiKOl, Fly,1b shouu thu rusulta for tua typical nuclal ' " ' ( **nd 4uPu (sphiirical oiiapu) with a ahoil aodal alngla pnrt ielaXival uclwmit, tjvnuratat) for thu nodlf isd harmonic osci l la torputuntial of Soeyvr und I'eri&hu? Ihw smooth rofurancw alnglauart ic la I tuul density fur thu two nuclai a i l yunuratad by thabtrutlnsky &«onrinu prucudun.' with a simarlng with para««tar• y - I . 2 ( Y » and a sixth order curvature correction.
-7-
and t = E + Z
a «Tda
where the coefficients a. are related to g(€) and its derivative* at
the chemical potential. It hsa also bosn shown that with enough number
of levels on either aida of the Fermi level the summation* in £q4.(5)and
(7) extend over odd values of the index 1 only. E* and t ara the
ground state energy and the excitation energy respectively corresponding
to the smoothly varying part g(€) of ttia IRVOI schsae and T ia tha
temperature. Since one also has E • E + £ , where £ and £ are the
actual ground state energy and the excitation energy respectively, thu
shell correction energy can be obtained frow the relation
The teat of the validity of the assumption of complete disappearance of
shell effects is that at sufficiently high temperature* (E -E ) should
be independent of the temperature at which C and £ are calculated.
This constant value is identically equal to the shell correction energy.
In tha lou temperature region where the influence of {Tgfe} peraiate,
the identity (t -t ) will show a temperature dependence.
Results and Discussion
We present hare results of calculation* of shall correction energie*
of nuclei by the temperature smearing Method for two typical typ«« of
aingle particle energy level schemes, the firat one generated for • thro*
dimenaionnl Harmonic ._illator potential and the second one for • realistic
folded Yukawa potfcn ial. It is shown that the tempsratura s*e«ring
method leads to a unique walue of the shell correction dnergy within
-e-
Calculated tunperatura dnpvndencv of tha antropy S and tha 'MJrtat ion »n»t9r d i f f crane* ( f - I ) Tor protunv and nautron in " ° P »Tha slnglo puj l lc lo leuhl sunomo uusd J» thu haraonlc osoiJllatorl«val schHaw uf imeyor «IVI puriiho? lHu brokan 1-tne in tntf(C - t ) uursut r plot raprnMinti th« taroth orii*r result t -E m
"V K T h b continuoua Xinu r«pro«ynt» result* obUlnad with
talo tarma In l u . ( O ) .
- 9 -
+0.2 PtaW,
Case i i Harraonic Usci.'Uator potential energy level echeae.
On* of the important features of thia lavel schaace is the absence of
• continuum in the en»vgy level sequence. I t Is for thj.0 type of lsval
scheme, that the Strutinsky amercing procedure use originally prcpcfcod
and has bsen successfully employed, for this level schews, tha avaraga
single particle level density is a pr ior i known to bat a second degree
polynomial in energy. Consequently, in Cqe.(6) and (7) representing the
aeyftptotlc temperafcute dependence of the entropy and excitation Bnergy,
the number of terms to be retained are only two. ' Fig.2 shows « plot
of tha calculated (S/T) versus T for protons in Pb. I t i« seen tiiat
Iho asymptotic temperature dependence of ( 5 / T ) ie wall repreaented by a
linear relation of tha form
S/T = a., + a3T2
Also shown in Fig.2 is a plot of (Ex~*£ ) versus T, calculated on the bnaie
of Lq.(7), where the coefficients •1 and (i have bean obtained from the
Slot of S/T versus T . It is esen that the shall effects wash out at
about 3 I*!BV and in the region of T^> 3 f'miU, (E -£ } approaches a constant
value which can be identified with the shall correction energy. Also
shown in Fig.2 is a similar plot of the calculated (S/T) versus T and
(£ -E ) versus T far neutrons in Pb, leading to identical conclusions.
In Table I, wa summarize thd results of calculations of shell correction
energies for a range of nuclei. Ths corresponding values obteinad by the
Strutinsky smearing procedure ara also shown in tha table for comparison.
It is seen that tha values obtained by the two methods agree within 0.2 f»«W.
Ue therefore conclude that for this type of level scheme, the Stiutincky
method and the temperature smearing method which have been shown to be
-10-
besically aquivolant, also lead to aimilar numerical reeulta.
Table I
Calculated shall correction enerQlea (WeV)
Proton a __ Hautr oneNucleus Present Strut insky Pre»»..: Strut insky
Method Method** Method Method
i -3.7 -3.8 -6.2 -6.3
-4.7 -4.7 -2.6 -2.6
i +5.7 +5.7 +8.2 +8.2
i +0.5 +0.7 +1.9 +2.1
+2.2 +3.1 +1.0 +1.0
+ Calculations have been carried out for spherical shapes oftheae nuclei.
++ Calculated with *fm 1 *2 1\Ci> for the smearing width paramatarand a sixth order curvature correction term.
Caae iit Raaliatic single particle energy level schemes generated for afolded Yukawa potential.
Ae different from the harmonic oscillator energy level acheae, aIngle
particle energy level schemes based on realistic shell aiodel potentials
of the Wood-Saxon type or of the folded Yukawa type have only • limited
numbar of bound levels. It has bean shown that for this type of laval
schemes also, one can employ the Strutinsky smearing procedure for the
evaluation of the shall correction anergiee provided one adda to the eat
of bound single particle energy levels, on artificial aet of diacrete
levels in the continuum region. We praaent here sons results of calculations
- 1 1 -
Calculntm] tiympHr^tur* dopend«nc« nf th« entropy S and t h *»«ciLjt.lnn unptgy dlf'eruncB (E -E ) for protons and nuutron* In/<tol'u (schurii.cl shopu). Tha •Inglw purtlclu lvval • r l i t m uasd! • the luvelu yanaratart by Onstarll ut • ! . ' tor a r t a l l a l t c tuliladrufc»w« potent I»J . rhe brukun Una i n tlie { f -C ) wursu* T plolt«pra«untH tt>» i i ru th oi-'iur nmli l t C - t " f " ' • (.untinuou*Una roprctuntc ihu r n u l t t ottaMHJ^wifn fTwn tSrna In t g . ( 6 ) .
-12-
uf ahell correction energies by tampaiatura smearing for ons such
3chon:B» generated for a folded Yukawa potential by Bosterli
ot al. This lave! echema included in addition to the bound Iavel3,
s .United numbs" of discrete levels In thu continuum region also upto
8ingla particla enr<J.-gy of 18-19 PleV.
Since no apriori knowledge exists regarding the functional form of
the averaga single particle leval density corresponding to this lounl
schema, it ia not known before hand how many tbrms will be required in
the asymptotic expressions for the entropy and the excitation energy
(£.qa,(&) and (7)). We therefore adopt ths fallowing, procedural Us take
the specific example of protons in Pu (spherical shape) Fig.3 shows a
plot of the calculated (5/T) uersus T for this case. It is seen from
the figure that the asymptotic functional form of (S/T) versus T deviates
from a straight lins. It is also seen from the figure that the range of
shall effects is as before about 3 MeV. Theriif jra, one can evaluate the
cytMTit; iants a at about 4 l*!sl/. Since the number of significant coeffi-
cients in the asymptotic B«ries expansion for the entropy (£q.(6)) is not
known, calculation of (£. -L ) is carried out with different number of
tannu in Eq.(6) and (7). A plot of the resulting shell correction versus
'.hfj maximum number of terms in £q.(6) is shown in Fig.4. It is seen that
with aauut 5 terms in the serie6, the evaluated shell correction reaches
a constant value with respect to the number of terms used within 0.2 MeV,
thereby giving a well defined velue of the shell correction energy. The
calculated (£ -£ ) versus T with these coefficients ara also shown in
fig.3. fllso shown in Fig.3 are the plots of (S/T) versus T and (E -E )
uersus T for neutrons in the same nucleus, Pu (spherical shape) with
similar results. These calculations have also bean extended for other
-13-
rtf.«'. Calculated ahell correction* arfergles a* • function af t»«of tataa In t>|.(b| ror tin. cea« or th« nuclvua " • f u .
( i l l ) Protonai •«»• 3y<M>«tric anconil HM1K anvpa, (1«) M««itrwtaiMa i «^«;i>»trtc aecuiKf bcrrlar ah«p*( (»> *r»|pnai aaaa aayaavttlc•vcuml bartler »h»p», (yl) Niiutronai aa«a MjraaatrlC «>van4 batflM•Mpa.
-14-
deformed nuclear shapes and for other nucleon numbers. Typical results
far the symmetric second barrier deformation enapo foe tha same nucleus
24 0
Pu are shown in rig.5 and Table II summarizes the shall correction
energies obtained by the present method Cor other deformed shapes rele-
vant to fission. Also shown in Table II are the corresponding result*
ubfainad using tha Strutinaky smearing procedcte. These calculations «r«a
of particular interest since i t has besn found that in specific instances,
sucr an for daformed nuclBai shapBS near the second fission barrier for
the nucleus Pu, the Strutinsky smearing procedure does not lead to a
unique value of the shell correction energy, since nsither the original4 10
plateau condition nor ths stationary condition of Brack are satisf ied.
Even in thaea cases, the present temperature smearing method leads to well
dsTined results .
It can therefor* be concluded that though the temperature smearing
oio:.:tidurc and tha St.rutinoky smearing procedure are barsicai'ly equivalent,
due to diPPuronaa* in tiha detaila of nuwuFical procsdurer ottopted, they
do nob necessarily yi«i1d identical result* for a l l level schemes. Uhil*
for the harmonic osci l lator l eve l s , the two methods yield the sans results,
Tor lsuel schemes with a continuum, the temperature smearing method yislds
a mure precics value of tha shall correction energy.
19 S
ISO
T(M(VJ
3
2
1 /
— ; * -
:
I/
~v-~.--'1 1 ' k—'
240PU -Protons
( 5ym 2nd barrtc' shape)
27-0
240Bi - Nrulrons
( Sym.Znd bnrfier shape )
M g . 5 . Uv l r i i l ' i t ed tcmuuratur* dep«ndunc« of ttio «plropy S »ne) tlm l | j c U « -t h n prmrgy djr» i r«i ice ( f < - t ) f o i proluns and neutrons I n I'u,huul» 9 I he Bymrwtrlc «ocunj C a r r i e r I|B I uiTi.it loo shapv. Ihu f i l n g l *p» I h I D I D K B I fic'inmP used It (OP iuuu ls y«nHt.it«i< by R o s t ' c Hut «!'.» ror a ii.'iijjHt. ic fulUml Vuksu* i < ' t> j r i t i * l . lh« hruktin l i n e• n l ' " ' ^Jlx"''*' wwrauft T p lot C L ' | I I U 9 H I I I S th« r e r o l h .x\,!t tvnult.' „ " ' - * x l r ' " * "onlimious ilnti tv fir'tr-'r.lv t lw ' usullt
-16-
TabJle I I
Calculated Shel l Correction EnsrgJBH
^ ^ Protona Neytron*Nucleus Present Strut insky Present Strut insky
Method Clethod flathod f!ethod+
2 AdPu y * 6.39 6.23 7.50 7.08(0o0(BpliBrl
cal shape)
2A°Pu y » 1.29 0.97 2.63 2.32Q.12(istbarrier}240Pu «* = 0.0 2.34 1.46 3.79 3.19(masB symmetric2nd bar r ie rshape)
240Pu Um 0.8 -0.53 -0.65 -3.17 -3.16(mast aeey-mmetric2nd bar r ie rshape)
- : : ; i i a :<;'.! nito ' " j " 1«2 "Kco for the amearlng luidth parameterand a s i x t h order curvature correct ion term.
V.8.RanamurthyS.S.Kapoor
'i . J .H. Nix, Ann. Raw. Mucl. ScisncB 2p 55 ; i 9 7 2 ; .
2. i i . Crack, J . Oamgaard, A.3. JenBen, H.C. Pau l i , tf.d. StrutinBkyand C.Y. Wong, Rsu. Mod. Phya. $±, 320 (1972).
J . P. Roller and J.R. Nix, Proc. I«tA Symp. Phy9. Chem. FissionJrd HocliGStsr, 1973, V o l . I , 103, IAEA Uienna.
4. V.f l . Strut inaky, Nucl. Phys. «95_, 420 (1967).
5» i/.S. ^aroamurthy and S.S. Kapoor, Phys. Letters 42B. 399 (1972).
6. R.K. Bhaduri and S. Uas Gupta, Phys. Let ters, 47B. 129 (1973).S. Oae Gupta and S. Hadhakant, Phya. Rev. 9£, 1775 (1973).
7. S.S. Kapoor and U.S. Ramamurthy, Paper submitted for publ icat ionin PRAMANA.
a. V.S. Hamamurthy, fl. Prakaah and S.S. Kapoor, This repor t .
9. P.A. Seegsr and R.C. Perisho Los Alamos Sc ien t i f i c Lab. RaportLA-3751 (1967).
-17-
10. 0. Brack and U.C. Paull, HueI. Phya. »2Q7. 401 (1973).
1 1 . * . Gilbwtt end A.G.M. Ccaaron, Can. 3. Phya. 4^, 1446 (1S65).
12. A. Polater l l , C.O. r i » o i , 3.R. UiK and J.L. «grton. Phya.Raw. CJj 1050 (1972).3.H. Nix (Private CMMunleaUona) 1971.
-19-
B. NUCLEAR PHYSICS
NUCUAH REACTIONS ANQ SP£CTRQSCOPIC STUOI&S
':l'..-:. 'X^\ .'.?. a-i '•-*» ?*r>t?is rj_n ** through Aloha Particle Canturg
Raaofiancn-j (PI.A. tauaran, O.R. Chakrabarty, N.L. ftagoouiansl and
H.H. Qza)
Thu present uork is concerned ui th the view of locating and
36studying the higher iaospin states in the asif-conjugate nuclaua Ar
Ar is at E «6.612 fietfa
through;*-capture. The lowest T « 1 states in Ar is at E «6.612ax
and the louaat T = 2 statea ia reported to ba Pt f => 10.86 PleU Fromex
( p , t ) reaction. ' The excitation region studied in this work is
>s/10.65 iisV to ^10.94 HeV.
32A S target (enriched to 99.9£) is prepared by evaporating Sb?S-
o;i go-id backing. The uatar cooled target of thlckneae 24 yug/cm (TJIQ kaV
for 5 ItaU oCJ uas borabardod with oC -par t ic les , from S»5 PteV Van d« Graaff
f\r.nfsXBve.tot at Trnmbay, in steps of 5 keU, steps being rsducad to h«lf
n:)3r a resonar.co. A 12,5 era (d ia ) x 15 cm Nal (T l ) detector at an angle
nf 55' 'Ji.ti: incident beam and distance of S.4 en from the target detec-
f-o(J thT f - rays o The axcitation function as obtained for thrae snargy
rogioiui o f f f - reya , is shown in T i g . 1 . 1 . Two sharp resonance* ara esta-
i.J.iehoJ at ^ ( i o b ) a 4.53 HeV and 4.69 flaV, E m 10.67 (1eV and 10.62 PIBV,
uhich decay predominantly to ground and f i r s t excited atats rsapsctivsly.
The ab&oluts strengths of the resonanceo were estisiated by coapcring the
• f -y io ld with that fcwi ng^.'T) reaction at E^ - 3.2 JieV resonance of
known otrength; The angular distr ibution has also been taken on the
Cgt - 4.69 PlaV resonance for the transition, rasonsnes-*2+(1.97 HeV) end
the XT analysis of the dsta for different spin choices or the resonance
waa aads for various values of multipole nixing ratio.
-20-
1JS«,l0*Ar t.(M.v)—n-m 1070 10K I O W ' iQ-t; » u t o w » • «
I1",''''111., „, 1
I I , , i l"' i
"'., '
JOOO
f«OC
E , . « ! TO 1 3 HaV
A,„
1
i'l 111
>J0 i«4 I H 173 »7« t.K l i t
e r • t . i TO n.i M«V
U) (H UD
g.1.1 Excitation function for the reaction 32S (ai , f )36Kr
ln th« c«»« of c<-oapturs on •vsn-even target, 3 valuaa
of raaonanca* arc liiaitad to 0+, 2*, 2+, 3~, 4+.... For tha E^ -
4.69 fisV raaonancCj, tha choloaa 1~ 4 3~ can ba rulad out bacauaa of
largo (12 alxlng naadad. Tor. tha c."-nlca of J > 2+, tha tranaltion,
Raa.-*2* (1.98 Half), la aithar pura HI or pradoainantly E2 ( 6>S0»).
Ruling out tha larga aultlpola alxing for thla tranaltlon from tha
raaonanca fron which tha ground atata tranaltlon la alMoat nagligibla,
tha M tranaltlon atrangth la 0.03 w.u. aa dataminad fron the raao-
nanoa atrangth. According to tha laoapin aalactlon rulP^T • 0 m
tranaltlon la Inhibitad In aalf-conjugata nuclal. Tha obaarvftd tranal-
-21-
tion strength fells on the higher sids} 'indicating the possibility of
T m 1 for this transition. The observation of wary small £2(^0.1 w.u.)
strength in th» ground state transition is consietant with this possi-
bility! ' The possibility J » 4 houewer cannot be ruled out from tha
prseantly available evidence. These results, as uell as the information
obtained on t , • A,S3 PleU resonance are shown in Tabl*. 1. Out of tha
two possible choices, 1 and 2 for the second resonance, the resonance
strength shows that, if it wars 1~, then possibly AT » 1 for this
transition.
Table 1
t^(LAa)*n«v)
4.69
4.53
cox
(lie
10 .
1 0 .
v)
82
67
S >(23+1 )£rf
2.2+0.2
0.96+0.13
a"
4 +
2 +
2 +
2 +
i "
Transition
4 +
2 +
2 +
2 +
i "
- • 2+
(1.97 MW)
(1.97 nail)
(g.a.)
- ^ 0+
(g.«.)
- * o+
(g.s.)
flulti-Polanty
E2
Ml 3
E2 <
£2
E1 3
0 .6
.1x10~2
0.21
.2x10~*
T
-
1
-
-
i
1. P.fi. Endt and C Van Oer Lsun, Nucl. Phys. A214 (1973) 1.
2. O.C. Hardy, H. Srunnadar and 3« Csrny, Phys. Rav. C1. (1970) 561.
3. t.K. Warburton, Proc. of Conf. on "Isobaric Spin in NuolaarPhysics", Florida (1966) 90.
4. G.A. Hokksn, 3.A.3. Hermans and A. Van Gunkal, Nucl. Phys.A211 (1973) 406.
-22-
2. j<n) Reactiona on Light Nuclei (d« Baiakrishnan, S.
S.S. Karakatte end M.K. flehta)
As s-d shell nuclei are well studied theoratieally, experimental
inf ox-watlon Aike compound nuclear level properties etc., on nuclei in
this rat,i0,-1 are useful in testing theoretical predictions. That way,
the study of l"<,n) reactions at low alpha energies (C^%1 to 5 fleV)
on light nuclei in the s-d shell region is one of the methods for
obtaining compound nuclear level properties in the excitation energy
range of 10 to 15 MaU.
Accordingly, the excitation functions for the reactions F(<*,n) Na,
29. 32 •
Si(*,n) S have been measured from near threshold upto about 5 MeV
alpha energy, using thin targets (~ 5 keU for E ^ » 3 deU) and a ATT
neutron counter and in fine energy steps (~ 5 keV). The excitation
functions shout in general many isolated resonances. If J of these
levels in tha compound nucleus ara known, partial widths can be vxtrac-
--•:'•••• ---.yj L. factors estirnatad. Otherwise, a statistical
analysis of the data is carried out, wherain one average* the excita-
tion function over large energy intervals and extracts an average alpha
strength function (assuming' n ^ V.). Further statistical analysis
the ltiwel spacing* and level width* is also carried out in thasa
19 22The f(°f,nj Na reaction axcitation function which was Measured
earlier with a thick target ("30 keV for E ^ » 2 n*V) (8ARC-768) ha* ba*n
remeasurad with a thin targat ( w5 k*W tot E K » 2 n*V. The excitation
function exhibit* Many J,«olatsd reaonanoa* (Fig.2.1 ). A* th* T r o f
these resonanca* are no: known, a atat1stleal analytic of the data h*«
been carried out and thi averaga alpha strength function ha« been
obtained. ^ ^ • 0.01+.001. Tha resonance anaroi** and Uielr uidthe
-23-
f l y . J . 1 . EKCit.ition funtLicifi Tor Hie tesctltin T (o< , n ) Na
from t M • 2.6 f*V tq £:„, » !i Motf
H«tBd.(Tabl« 1 ) .
TABLE 1
1S f (
CHtS(«eW)
2.600
2.660
2.730
2.955
3.150
3.250
22eC.n) in Rasonancaa-noaitiona and Mi
Width(kaV)
50
25
35
43
25
25
CR£S(naV)
3.300
3.575
4.095
4.170
4.490
4.605
dtha
Midth(kaV)
25
IS
45
45
65
45
Noia: Only tha widths of strong and dl t t i .net rssonartct* arctabulated.
This widths ata not corractad for targat thicknaaa( ~ 6 k*V for 2 ItaV ^ ) .
-24-
29 3229 32Tha Si(^,n) S reaction excitation function using thin target
measured eariiar (to bs published in Phys. Rev. C, 3an 1975), indica-
ted the presence of gross-structure* near the threshold. This prompted
to accurate measurements in this energy region to study
29 32
well thane broad intermediate width structures. The Si(^,n) S
reaction excitation function measured with a thin target ( ~-6 kaU for
t^ a 3 CleU) at energies near the threshold, show »nree broad struc-
tures with widths of tha order of 80-100 keU. The three broacf reso-
nances have been least squares fittod (fig.2.2) and individual resonance
widths extracted after correcting for contribution from other resonances.
The alpha and r-eutron reduced widths of these ere very large compared
to alpha and neutron single particle limits. Further, the average alpha
strength function is quite high for this region of excitation energy.
EXCITATION ENERGY N ' ' S (M«V)8.6(0 «7«0 MM 8-95S SOU 9.OI HIS 9.307 9.396
5 u ti fS £10 t* 2-2 M I* It ISNQDENT ALPHA ENEROY-MtV (Lob)
29 32Intermediate ui. I lh stujctures Ln 5i(o( ,n) S reaction
mint tlitosh'jlU.
The absence of fine structures and the large values of the reduced
widths lend support to a theory of explaining these structures ae door-
way states. Visu.li.ino. the 2 9Si t.rget as if on. neutron i. outside
-25-
28 20
a SI core, the (V.n) interaction on Si target may be considered ae
two particle one hole type interaction. further work in explaining thaaa
intermediate width structures on theee lines is in progress.
**< lfc.'!f*X..P.r.,.55 (P•n ) 5 S r e reaction (£. Keilae, Y.P
-« Saini, A. SanerJee*, N.K. Ganguly* and M«K. Clehta)
Cc EC
Tha measurement of Fln(p,n) fe reaction excitation function
which mat started last year, was conplated with the target thlcknaaa
measurement. The total (p,n) croaa aection waa extracted for tha
proton range from 1 .35 fleW to 5.4 fleV; ' A faw atrong and distinct
laobaric Analogue Resonances (JAR) were located at Ep - 1.37, 1.455 and
1.561 fieV. Hence more accurate study of these iARs was started. As
the IARa ware located at and below 1.5 fieV and aa tha 5.S deV Van da-
Graaff accelerators in general could not focus wall below 1.5 PieV dome
voltage, Piolocular Hydrogen beam (HH ) at twl'je the proton dons voltaga
was used so that the Molecular bean on braak up at tha target surfoce
gave two protons of tha required energy (Half of HH beam anargy).
Hcwovor, the IAR at ~1.5 (1BU waa Measured with H beaa alao for nor«a-
lisatiun purpoeaa. It waa obaarvad that tha widtha of thia raaonanca
u^rs different for tha two typaa of beaam, H and HH . Thia discrapanoy
had bean txacad back to tha inherent raaolution probla* one would encoun-
ter if ana ueed tha HH baaai. It la Mentioned In tha literature that tha
HH beaM broke up into two protons and an electron with dlaaoclailon anargy
of ~ 2.6 aV and if one aaaociatad with each proton an internal anargy of
1 aV due to braak up, It would introduce a aaxlaiua) clasalcal anargy apraad
of +2 keW in tha laboratory If tha anargy of tha protona (bafora braak up,
in tha cantra of aaaa waa 1 HeV. This way on* Might na able to explain
tha diaerepancy In tha widtha of tha narrow reeonanca we ware aaaaurlng*
-26-
Thus these studies have shown that one should not use the molecular hydro-
gen beam for studying narrow resonances because of the poor beam resolu-
tion, brought about by the breaking up of HH beam.
However, the l«H measured at ~/1.5 MBJ with proton beam was analysed
to get an idua about partial widths and speCtroscopic factor for
that leval. ^
Further measurements with proton beam and thin Nn targets
on the same 3 IAKa ara planned for futura.
•Members of l/.t.C. Project.
1. S. Kailas, Y.P. Uiyogi, S. Saini, 5.*. Gupta, N.K. Ganguly,U.K. fiahta, A. SanerJae, S.S. Kerekatte, Nucl. Phys. andSolid State Phys. Symp. (1974) Bombay (To be published).
4, Study of (o.y ) Reactions (M.Ai Rahman*, PI.A. Awai* and S.K.Gupta)
In order to investigate the gamma decay of isobaric analog r«so-
"anc»5 in 2 8Si, 52Cr and 55Co the reactions 2?Al(p,"O, 51V(p,tf) and
54
Fe(p,^ ) have been studied. The resonances in these reactions were
located using a 12.5 cm x 15 cm Nal(Tl) detector. On the resonances
gamma spectra were taken using a 20 c.c. Ge(Li). Angular distributions
were also measured at some of tha resonances. The gamna decays of the
levels et 13.707, T3.96D and 14.007 in 8Si and 12.785 and 12.795 HeV
in Cr have been measured.
"fiember of Atomic Energy Centre, Dacca, Bangladesh.
5. ghane Isomer Excitation using 14 PleU Neutron Bombardaant
(A.L. Athougies*, S. Kailas and n.K. Plehta)
The study of the excitation of shape isomera in U isotope* started
earlier (B.A.R .C..-768) using a combination technique of recoil gaonatry
and makrafol treck ^dtector, continued with further measurement* of
leoaer yields^ and—standardisation of detection teohnique.
Spontaneously fissioning Cf source of known strength waa ueed «9 a
standard fission source to products fission tsraske in tlvs wakrofol datee-
toc. Those track* wars etchsd undsr standard etching condition*, (using
&H NaOH far half an hour at 6Q°C) and spark count<sd using the eparh
counter a» ciascribtd earlier. Thus etching and sparking techniques fiawe
been standardised.
As the yield from the flssionieoner axperimsnt is very low, back-
ground yield from the chamber contaminations will heva to be completely
eliminated. This background probierr from fission chamber uaod for irra-
diation has been eliminated by lining the chamber walls uitn aluainlsad
Mylar.
Further irradiations utilising larger neutron fluancs are in
23 B' 235
progress for both U and U targets as well as the background
monitor Th.>j££ff i?,cmc?iu% Phyai.es Department, St.Xavisr's Collage, 9ombay.
6. Nuclaar Soectroacopic Studies in tha mass 75 runion (C.U.K. Babe,
V.K. AgartD«JL*t S.(1. Sharathi* and B. U i » )
Oeteiled nuclear spacSroscopic studia* of the law«ls In As,
5e, 9 ' Xr have b««n «ade through (p,n) reacftlona on Ca, As and
f Br. These studies include gamma-ray spectroscopy (f-ray spectre,
Y -fcoincidence spectra with Ga(Li)-Ca(Li) coincidence system), internal
conversion electron spectroscopy using the eix-gap 'orange* spectro*etar
end life-tine meeeureaent studies. Ae e result of theee studies level
•cheaee of the ebove eantioned nuclei have bjen obtained.
The main conclusion drawn from theee studiee le that the odd neutron
nuelel in this region enow well developed rotational bende and hence ere
deformed. Severel of these band heads have been identified with the
-28-
Nilsaon states. Thsae results have bean published in Kef. 1-3.
1 . C.V.K. Baba, S.fl. Bharathi and 8 . Lai, Pramana 2., 239 (1974).
2 . Y . K . A g a r w a l e t a l . , I b i d 3 , 2 4 3 ( 1 9 7 4 ) .
Z. -i^. a i - t f i ra tn i o i a l . , J b i d . ±, 2S ( 1 9 7 5 ) .
s o f T . I . F . R *
7, Spet;trp3coDv qf V uifch (n.nT) reactions* (S.K. Gupta, S. Saini,
L*V. Narajoshi and M.K. Ilehta)
Information on the low-lying levels upto /*•* 1.9rteV excitation of
the doubly odd nucleus V has bean obtained through Ge(Li) - Ge(Li)
coincidence with the Ti(p,n"!f) V reaction. The measuramenta wera
50 9
carried out using enriched TiO2 vacuu* evaporated ( <v 10 uga/on thick)
tranamisalon type targets on thin carbon and aluminium filae. Bcwnching
ratios have bean measured and tentative apin parity aaeignnent* have been
nada. A detailed comparison with other meacurenenta racantly reported
have also been made. The summary of the raaulta ia given in Table I.
The experimental evidence presented in thla work indicate* that
seniority may be a good quantum number. Therefore assuming tho lowest
seniority wave functions for the V nucleua, we have calculated the energy
levele, the olectric quadrupola moments and the magnetic moment of the
ground state, the B(E2) and &(fl1) tranaltlon ratea and compared them with
the experimental results obtained in the present study as wall as with the
earlier data. The calculations ara liatad in Table II. Only ths magnetic
moment is of the right order c« magnitude. Indicating substantial admixtures
in the wave functions of components other than of £.*- orbitale.
(•To be published in Pramana)
-29-
LayelNo. prsosnt
Table I
Jf Decaygamma-raye(kaV)
BranchingRatio*
01
14
15
16
0
226.0+0.3
360.5+0.5
835+1
939.4+0.5
909+1
1301^1
1332+.1
1401+1
1517+1
1677 el
1702+2
1720+3
1725+2
17
18
1760+41766+8
18131?
3
2$
3 T - 5T
3 + - S +
226.0+0.3
94.3j;0.3320.2+0.3
35.5+0.3129+T
33.1+0.3
(835+1)(517+1)
683.4+0.3(909+1.0)
90911
94311
945+1
493+1
1085+11081+1
1106+11140+1
1161+1
117311120511
275+0.537577+0.61288+1132011
79312
133112136312
149912140512
100
98.5+0.21.5+0.2
99.3i0.20,7+0.2
100
67+.1S37+15
100
100
69+531+5
100
12+4
16+74
88+512+5
86+5
43+857+6
18+.544+720+718+7
100.
56+1144+11
91+59+5
21+113 T 142412145712149312
Theae aplf, and parity aaalgnnante ara baaad on the aar l i e r Maaaurenvnta atSmith at « 1 . Phya. Raw. £7, 1099 (1973), Ricksl at «1 . Nucl. Phya. ft232.200 (1974), Tonita at a l . Nucl. Phya. A232 417 (1974) and our work.
-50-
1 .
2 .
3 .
4 .
5 .
Property
(Juadrupole moment oY g.a.
Magnetic moment of g.a.
6(C2) for 22b ketf level
E2-W muitipole mixingamplitude
8(£2)32Q , . , „ ,e(ni )94 o r
Table I I
Expt.
(t)0.4
3.348
110+20
0.035+.096
54+7. G
Cal.
+0.013 barns
3.30 n.M
19.4 a2f«*
-0.0027
i.009.2f-V(n..)
Ret.
1
1
2
3
presentwork
I." Ifmf !tf9c for 356 keV ietfel 127+36 0.013o2f*V(n-*>2 present
1. C.fi. Ledsrer, 3.0. Hollander and I- Perltnan, Table* or Isotopaa,Sixth Edition, 3ohn Uilay 195B.
2. G.I1. Temmer and M.P. Haydanberg, Phy«. Raw. 104« 967 (1956).
L.Ut. Gagg, t.H. Gear and £•*• Wolickl, Phys. Rav. 104. 1073 (1956).
3. S.K. Gupta, S. Saini, S. Kailas, S.S. Korskatte and L.3. Kanatkar,Proc. of Nuclear Phyaica and Solid State Phyaica Synpoaiua 168.35 (1973).
3< fVuclear Data Measuraaanta (H.fl. Jain*, S.K. Gupta and n.K. Mahta)
Preliminary neaaurMsnta have baan carriad out to *aaaura tha
232(r,,T) for Tl< using the activation tschnique. Tha activity dua to
233 232Th produced, fro* Th(n,T) raaction in a foil, Mould ba obtained
233by maasurino tha intensity of gaane rays ftoa Th decay. Neutrons
of known energy would be produced by the Li(p,n) reaction uaing the
Wan de graaff accelerator. As an initial atep the ga*e>« epectruaj of
an irradiated *22Th foil hae been studied with a 27 o.o. Ce(Li) over
a period of three houre. Five photo peaks suitable for carrying out
tha activity counting were obeervad Mth energy 06.5, 162.5, 169, 459
•nd 671 kaV. Tha neaeured lntwultlee of theas different peeka were
-31-
observed to decay at the same rats. The measured relative yields were
found to be different fta* those published one. To overcome this
problem ve ate planning to measure Th(n,iQ capture cross section
197for thermal, neutron with respect to that for Au.
•flenber of' Kyperimental Reactor Physics Croup.
9. ,$)S>get; a of Doubly odd nuclai (&. Saini and S.K. Gupta)
!• Introduction
The 3poctra for doubly odd nuclei with minimum seniority utae—
functions for both the odd groups wera calculated by Oe-shalit and
Schwartz using zero range approximation. Later Oe-shalit and
Walecka did consider the effect of finite range of the interaction
but this approach has not been persued much in the literature. In
the prasent work a schematic interaction consisting of the delta-
function interaction plus the long range quadrupols-quadrupola inter-
action has been used to calculate the spectra of many odd-odd nuclei
following the work of Schwartz and Deshalit and Walecka , the analytic
expressions for the energy levels for the assumed interaction can be
written down.
The schematic interaction is assumed to be of the form
where V Q is the strength of delta-function interaction, eC i« the strength
of spin dependent part of V is the fraction of long range interaction.
Using the lowest seniority wave functions, the energy levels can
be expressed in tjrrr.d of matrix elements • .r the two particle configure-
-32-
The constant i n {2) la independent of 3 .and la given by -F £ 0^, -^7( i -«C) t
where F ia tha radia l integral and
Then energy leve l * for the interaction given in \'i ) are given by
Using the harmonic oaci l lator wava functiorit, with harsonic osci l lator
paraneter b - J - ~ a 11,016A' f e r a i , the energy lewale of sons odd-odd
nuclei were calculated.
I I . PlacuBBion
In the achamatic intaractlon ( 1 ) , thara are three parameters naaely
V , VQ ando^ , which wire auitably adjusted to gat tha baat f i t to tha
oxperiaental lavala . In aio«t ot tha oaaas, our calculations, raprodiwa
tha apin aaquanca and tha enargy of t h " faw low-lying lavala aa shown
in Fig. 9. i . ^ . The aa»a paransatara do not glut tha batt f i t for a l l the
nuclei in the aana aub-ahalls which la not deairabla. Thla probably la
due to tha fact that whan wa use a trunaated configuration apaoat the
i I
- 3 3 -
i t
I I
I-.-,•„ 0~ .-, - —v*.. | J N « >^ iff •
!! I I
* 1 f ( f ) 1
8 g g §
Jf.
I !
I I
I I l"
I ? ! § g gO w *
i ]3 Is!
It
1 8 I Ii i i *
8 1 « §
- 3 4 -
y , • ooi
1 i in
b . 2 15' F«imp
t ' • l i 3 J M . V
parameter hsfe to be suitably renormalized for each nuclau*. In »oet of
the canes, the o -function interaction alone cannot reproduce the experi-
mental spectra. The addition of small amount of long range interaction
brings the spactra into a doaer agreement with the axperiaantal data.
1 . A. Oe-Shalit, Phya. Rev. 9' (1953) 1479.
2. C. Schwartz, Phya. Rev. 94 (1954) 95.
3. A Da-Shellu and 3.0. Ualecks, Nucl. Phya. 22 (1961) 184.
10. Proton, Knock-Out Reaction!. a ornba for tha Cluitar Slzaa l,nNuclei (8.K. 3ain and A.K. Jain)
Thara. have been increasing evidences that Many nuclai exhiDit
cluster structure. The clustering probability and the intar-olustar
wave function of these nuclei are studied by tha cluster knock-out
-35-
reactiorw, using distorted wava impulse approximation (QuIIAj '
Houiaver, the structure of the clusters themselves, apart from some
indirect indications 'have not been studied by any direct means. In
thi» note, us propose, if the single nucleon knock-out reactions, on
clustering nuclei, are studied in collaboration with the cluster knock-
out reactions, they can provide the information about the structure
of clusters in nuclei. As an illustration, tie haue analyzed the
(p,2p) reaction at 155 ("lev" on Li, in DUIIA, and (e,e'p) reaction at
700 MeV on 6Li and Li in PUIIA. The 6Li and Li nuclei are described
as having alpha-deuteron and alpha-triton structures respectively.
The inter-cluster wave functions for them are from the OWIA analysis
of the (p.pd) and (p,pt) reactions 'and the B.E. work of Tang et alV.
For deuteron and triton, in Li, we have used the Gaussian for*, with
_ 6
size parameter ot. Following Tang et al. the residual nucleus He is
described in cluster model and He by a Gaussian neutron wave function
plus an alpha particle.
In_Figs.1-3, we have olotted the dependence of the recoil momentum
distribution, P(Q), and the angular correlation distribution for (p,2p)
reaction on a for the knock-out of I* 1 proton, along with tha experi-
mental points . These results clearly demonstrate that tha recoil
momentum distribution is quite sensitive to the size parameter of tha
clusters. The comparison of the calculated end tha experimental results
suggest that, in comparison to their sizes in free state, the deuteron
in 6Li is contracted to <r 2> ^a 0.968 fra (a- 0.8 fm~2), and tha
triton, in Li, on tha contrary is elongated to < r > "oj, 3.162 fm
{oc m 0.1 fi* ). The radii of free deuteron and triton are 1.85 and
1.70 fm respectively. It is also important to nota that, lika our
earlier work on c\ •'both the (p,2p) and (e,e'p) data on 7Li, ,con-
-36-
Fig.10*1 f iecol l •moiimnt.um dla'tributiun Tor knor.k-eut of tp ,proton.
from H
F l y . I D . 2 flecoii nioi)'P»tum d l e t r i b u t l o n fpr knock-out of ip proton
from Li
Angular coi-falatlun r o r r.f,r.Ck-aut of 1p proton from Li,
-37-
•latently require the same size of triton.
There is, however, disagreement between the calculated and
experimental results on 6'7Li (e.e'p) beyond recoil momentum, Q -
100 FteV/c. The reason for this probably lisa in the inadequacy of
the impulse Approximation for the description of the reaction dynamics.
1. A.K. Jain, N. Same and B. Bnaerjee, Nucl. Phys. 0142 (1970) 330*
A.K. Jain and N. Sarraa, Nucl. Phys. A195 (1972) 5Q6.
2. 3.Y. Urosaiord et al., Phys. Rev. Lett. 32, (1974} 173.
3. i.C. Tang, K. Wiidermuth and L.O. Pearlstein, Phya. Rev. 123(1961) 548.
4. fi. Shanta and B.K- Jain, Nucl. Phys. A175 (1971) 417.
5. H. Hiramatsu et al., °hys. Lett. 44J3 (1973) 50.
J.C. Roynetts et el., Nucl. Phya. £95. (1967) 545.
11. Deuteron Contraction Effects in the dfd.tip React|pty fll.KV Jain
and N. Sarma)
The.behaviour- of the' constituents of' a deuteron in the presanca
of another deuteron may be studied through a reaction such as the
d(d,t)p. This reaction at medium energies and forward anglaa corrae-
ponds to the incident deuteron picking up a neutron fro* the tacgat
deuteron. The matrix element for this reaction should therefore
depend on the form factor of the neutron in the target dautaron. Th«
reaction ie therefore interesting to study beoauas recently thata ha*
been a great deal of evidence that the deuteron ahrinka in the preaane*
1 2 3
of another nucleus such as the alpha particle ' ' . There art eeveral
problems in the analyaia of this reaction. First, the antiey«MetriS*»
tion of the four nucleons in ths initial atata has to ba oonsidaraa]|
the two processes, stripping and piok-up ara then accounted for in th«
-38-
calcu.lation. Secondly, the longer range interaction (due to the large
size of deutsron} between the two dsutsrons is important and this thara—
fore rsquireu a distorted wave analysis. A previous analysis ' neglected
this last sspect and tl.air conclusion was that it was necessary to treat
distortions axplicitly in order to get any satisfactory agreement Jij.th
experiment.. Howevor, an accurate distorted wave analysis requires
evaluation of six dimensional integrals.
The analysis of the d(d,t)p reaction haa therefore been carried out
using a distorted wave formalism with full antisywnetrizatlon in the
initial stats. The formalism allows ths internal wave function of both
deutarone to be varied. The alx dimensional Integral has been simplified
u3ing ths local W.K.8. approximation. A different approximation, in
which tha separation of coordinates is based on the fact that the triton
wave function is highly localized and tho distortions do not change over
this range, has also been tried. Tha preliminary results indicate
that the agreamsnt with experiment should be satisfactory.
1. A.K. Jain and N- £>arma, Phya. Letters. 33B, 271 (1970).
2. H. Jacobs, K- Uilderrouth and E..J. Uurster, Phya. Letters 29B.4S5 (1969).
3. 3.V. urossiord, C. Costa, A. Guichard, n. Guaakow,. A ,K. Oain,J.fi. Pizzi, G. Bagiou and R. deSuiniareki, Phys. Rev. Letters32,, 173 (1974).
4. oi.f.H. Van Oars and K.U. Srockman, 3r., Nucl. Phys. 4_8, 625 (1963).
12. QButaron Cluater Contraction and the Quasi fraa
6L1(tj_, to]^He (A.K. Oain and N. S
The ^tsructure of deuteron cluater in Li nucleus can be studied
in the quosi-fras Li(d,tp) Ha reaction . In the analysis of Such a
reaction tha free dvd-*t+p cross section should not be used in the
impulse approximation because tha deuteron cluster is expected to ba
-39-
6 2 3
much smaller inside Li than a free dsuteron • . Seeldee thia centra-
ction dua to the alpha cluster th« dsuteron cluatet ia expected to get
derormsd under the influence of the incident dautaron. Therefore •
complete analysis of Ll(d,tp) Ht reaction should incorporate felt* tfefef*
Nations of the dauteron cluster caused by the incident deuteeon aa well
as the bound alpha cluster.
The formalism for our calculations on the U(d,tp) Ha reaction
takes into account not only thaas deformations but it incorporatM the
optical Model distortions of the wavee in the incident and outgoing
channels also. Antieymmetrization of the Li wave function ha* town
neglected and Justification for this neglect darivaa from the fact that
the reaction is extremely localised on the nuclear surface. A program
has been written using the infinite partial wave praacrlption develop**A
by us. The code has bean written to use lass memory and laaa time thanthe Li(p,pd) Ha program developed earlier. Parameters for the d- He Jm
4 4the initial state and for the t- He and p- He in the final state neve
been located.
1. 3.V. Grosaiord, C. Costa, A. Guichard, 1. Gusakow, A.K. Jain,3.R. Pizzi, G. Bagieu and «• doSwinisrski, Phye. Raw. Lattera,32j, 173 (1974).
2. «.K. Jain and N. Sarma, Phya. Letters 33B, 271 (1970).
3. H. Jacobs, K. Wildermuth and t.J. Uurstsr, Phya. Letter* 2M.455 (1969).
4. A.K. Jam and N. Sarma, Mucl. Phys. A233. 145 (1974).
13, On the Fundamental Representation of Stl(3) ornun (S.K. Gupt*
and I.V.U. Raghavacharyulu)
The mathematical propartiae of SU(3) and its gsneralisatlon tU|n)
groups play an important role in nuclear end elementary particle
physics. An SU(n) group consists of (n-1) diagnal alamenta h ••
-40-
n(n-1) nondlagnal elements e^. Tor tha fundamental reprecantation of
1 2h '8 Biedenharn deflnaa a new baeia ' in tarma of tha real coeffi-cient* V . which aatiafy tha following relation*$
Jfc
Equation (1a) is derivable from the eqn.'(1 ) bscauae i t impliaa
are eJareentso of an orthogonal matrix with Indies* i • o to n-1 andAt) _1ft "$. \(0 -
1 « i ton . If A » • n ' then null trace condition £. *t -°**' -1ftis obtained for tha diagonal matrices h. defined aa h * (2n) '
^ *••
where £, Is a matrix having 1««U elemsnt equal to ona and remaining
aa zero. In general the above mentioned aquations for X* leave
1/2(n-i)(n-2) quantities undeterminvd. Howfevar, for the SU(2) group
all the elemente or fundamental repreasntation are uniquely determined.
for the SU(3) group only ona number la undefined, and-therefore a
number of fundamental representations can ba written down uaing thia
•ingle parameter. For example the diagonal matricea h.'e can be written
down in terms of withwith "X'm given by t* ' • (2)~^0, J-, •- (6)^(28*1)0. 7^ ( 2 ) - -(6)^(S+2)0 and
3 - -(6)1^(S-1)0 where 0 - (S2*$*1 f^2 and $ la a real parameter.
Giving different values toS various fundamental repreaentatlon for 5U(3)
group can be obtained which are uaad by verloua authora.
1. L.C, Siedanharn, J. Hath. Phya. 4 (1963) 436.
2. A. Partenaky, 0. Clath. Phya. 13 (1972) 621.
-41 -
c. fission PHYSICS
1 . Onesrtaintiaa in the Sftall Correction Energies obtalnad by the
Strutlnskv i wefehad. tas.d.af'armetl nuclear shapes relevant to f i s s i o n
! V ;-•, fU j-aptirthy, M*» Prakash end S .S . Kapoor )
Jo trts Tirt-ir Ps?sf- years numerous calculations of nuclear deformation
C':t6ntjii s."i.;rc>y p-urfacss have been made basaci on the now well known
ftscrossopic-aiJsoEcopic approach. These calcuiaticns with suitably
sxtrepoliteci i inyls particle lsvel achemaa for deformed shapes, have led
to the prbdictsd existence of a secondary minima in the deformation poten-
t ia l energy for nuclei in the actinide region. Moat of these calculations
have been carried out on the basis of the Strutinsky smearing procadura
which genaratos a smooth single pett icle level density lT(t.) using which
the shell correction i s obtained from the relation
•Jharc , \ I E ths Fsrtni energy, %, the deformation of the nucleus and Q are
th.3 i:.:wla /jOL-jicle model energy leve l s . In order thai this method givea
- asv'oun uoluf cf thB ehell correction "^U"' i b i s nacBOaary that the
q;jt<n;;j.cy " }j[) * he independent of the nonphysical parameters <>f* and p that
.jp(i.3«r .'.;i rj(i£). This plateau condition has been shown to be satisfied in
several casas, and the calculation of the potential energy in the past, have
therefore assumed the fulfilment of this condition a* a general feature of
the Strutinsky prescription. wc-«wBr, in those cases where the plateau
condition la not satisf ied , the stationary condition putforth by Brack and
Paul! hae been used and; waxiwaur uncertainty in the evaluated shell correc-
tion is reported to be around +Q.3 fleU.
In the pr»«snt work a detailed etudy of shel l correction* obtained by
94 Pi?*°NlX LEVELS
I
f i g . l . l t«lculat«d ah«ll jgrr actions ' ^ y for protons andnoutrans in ,'Pu as a fDOttiin or tfi« HXSSI ingjiaraoiMUr ' y 1 and poiytiomi.il 'p1 jhich eppaat ing(t)« fi«auit» 3t« shoiin fjc Jirrnrent udluer, ofthu «»S5 symmntric d«rornmtlun patimator "y". Theliivula u»ad am those fjffosralad by Nix fnr a r e a l i -s t i c fuldtfd Vu M*a potuntial.
-43-
ths Strutinsky procedure has bsen carried out in ordar to examine the
uncertalntlsa in the shell corrections for all nuclear shape* relevant
for fission barrier calcu' .tione. The result" of these calculations
for repreoenfentii's values of ths symmetric deformation parameter V ar.
24 0chcun in Fig.1.1 for protons and neutrons in Pu respectively. Va
have also shown in tho figures by vertical lines, the values of the
shell correction which are generally used ( Y » 7 and p • 6) for tho
calculation of deformation potential ansrgy surfaces.
It la surprising to sse that, in the framework of the Strutinsky
procedure, neither the Sirutinsky plateau condition nor the Brack sta-
tionary r .idition leads to a unique value of the shell correction energy
for several outer barrier deformations. Calculations carried out for
different nucleon numbers (2 » 84 to 102 and N » 136 to 154) at a defor-
mation near the symmetric second barrier haws revealed that the failure
of fchs plateau condition and the stationary condition is not United to
240the specific case of g/(Pu , but is a general feature for all nucleon
numbers in this region. On the basis of these calculations, we emphasize
that foe any quantitative calculation of the fission barrier heights it
ie necessary to establish the uncertainty in the shell corrections obtai-
ned by the Strutinsky method for all relevant shapes. It is further
pointGd out, that for the level schema used in this work (folded Yukawa-
potent ial) the height of the outer barrier for mass symmetric nuclear
shapes is not uniquely determined by the Strutinsky smearing procedure,
with the result that one cannot draw definite conclusions regarding the
relative heights of the masa-aymmetric and masa-asymiietric barriers at
the outer barrier shapes. These uncertainties may become critical In any
dynamic calculation involving the full deformation potential energy surface.
-44-
1. «. Br«ok ct al.. Raw. Plod. Phys. 44_, 320 (1972).
.2. V.PU Strutinsky, Nucl. Phye. A95., 420 (1967).
3. PU Brack and H.L. Pauli, Nucl. Phys. A207, 401 (1973).
4. P. dollar «nd 3.R. Nix, Proc. IACA Symp. Phys. Chen. Fission,3rd Rochester, 1973 Vol. I, p.141, IAEA, Vienna (Oiscussion).
2522. Tr»Jactory Calculations in Spontanapua Fission of Cf
(fl.K. Chaudhury and V.S. Rsuswurthy)
Th» work an the trsjsctory calculations was continuad. In the
firat version the input > .ifornationa wara tha alpha partiela anargy
and angular distribution and tha fission fragment energy distribution
Toe varioua «ass yatici and by tha nathod of aaxiajun likslihood,
tha valuaa or Initial parmusters wara obtained, which QM^O vary aatia-
factory fit* to «oat of tha experimental rsaulta. Hare in this work
wa hawa triad to obtain Information regarding the initial parameters
by having only tha anargy distributlona as tha input. Tha probability
for a particular sat of 0, X and Y waa assigned as
neglscting the small correlation term in this exprsssion, which will
bo considered later, and this probability waa maximlasd with raapaet
to 0, X ant. 1 to giva tha moat probable valuaa of these paraaatars. It
waa saan that two aata of 0, X and Y can give rise to equal amount of
fit aa far aa the final enargias were concarnad. Tha alpha particla
angles corresponding to theea two aata ara giwan in Fig. 2.Tfor varioua
4 2naesee along with tha results of Fraanksl and Flusa at al. Consider-
- 45 -
100
§90oCD
z
80
70
rFlussetal ^heavy
Q « o o ° ° RigM.o
Fraenkel
87 9» 95 99 103 107 111 115 119123MASS NUMBER
a r U c i e u n q l u u l l l , rB(ipOct. t o n e h t f r 3 g m e n t f o r
tho tau Buts uf the solutions, cumpaiaj with thu Bnpuri-">wntal ruaults .
ing tha awporifflontal uncertainties, i t i s seen that none of the two
solutions can !JB rejactad. So both ths rasults umto aasignsd equol
probability ani wontacarlo calculationa uara carried out to obtain
wacloua final Ustributiona and corralationa. Aa axpectad tha alpha
psrticla and fission fragnont kinatic onargy diatributlona ara rapro-
duoad vary Mall, Tha arfgular diatribution aa calculated fre« thaa*
i n i t i a l diatributiona ia eoaparad with tha axpsrlitantal diatribution of
riuaa at al in f ig .2 .3
-46-
Fluss et alCALCULATED
60 70 80 90 100 110
in
z
at3
150
10G
'50
\
-
a)
// •
/"
i
— EXPERIMENTAL•••CALCULATED
"X"
VEXPERIMENTAL..CALCULATED
15 25 35 160 160Ep.MeV
CulculBUd »nd «xpcrlmont«l alphd particle annular andon«rBy dlfltrlbutiona ((e) and (a)) and fls.lon frtgnantkinetic tnaryy d(itributlona (b).
-47-
|18O
J70
ISO
.-CALCULATED— EXPERIMENT
(a)•
1 1 ) 1 1
5 10 15 20 25 30
iLJ
I f iIO
16
14
\2
•
X
am
*
t
••• CALCULATED• # xxx Mehtc
• - ( b )
* * xX *
X
1 I
et at
•X
X
i
160 170 180 190 200
r ig .2 .3 ( • ) l4lcul£tHd toirBlotInn of C versus C us comparedwith BxpariiBental ra&ults. Oi.(b) talcultU'iij ualnnB or f . u«rsu9 P compared with tfieVHpwrlmantul rosultc.
- 4 8 -
1
24
22
20
18
16
14
»
*x
•
-
-
XXX
• • •
x«
X
• x K x
•
1 1
CALCULATEDTsujl * t at
X
•X
•
•
i i
60 70 80 90 100
n*,, c . T « ; r ^ calni)Ui8d ^
Other correlations like f_ warsua t , t weraua Cr and C
varnua « a» calculated are conparad with tha experiwent In fifls2«3»3*S
It in aasn that tha agree*ant ia quite good, which aupports validity
of the Initial parameters.
- 4 9 -
cn
ICD
80
f ^ xxx CALCULATED* a ' • • • Fluss et ai
CD
a
2 6 -
44-x x x
X X
10 15 20E« , MeV
25
(b) CALCULATED
xxx Fluss et ai
. • ' I*!_L
18 22 26
*. MeV
n«.2.5 Variatiun of 5^ L »lth L , (b ) Uariatlon or (J- with E .
I t was «aan that inclusion of the s^all correlation tar* in tha
axpiaaaian of tha probability did not altar tha valuaa or tha in i t ia l
para»atara appraciably« Further work on tha interpretation of tha
waluee of in i t ia l parcaetata and correlations aaono, thaa ia in pngreea*
-50-
1 . C.K* flahti, 3* Poitou, K.Rlbraf and C. Singnaribianx, Phya.Raw., C7, 373 (1973).
S. «»3* Fiuss, S.B. K»«f»«n, E.P. Stainbarg and B.O. Ullkina, Phya.Haw. C7, 3S3 (1973).
3= fUK. Choutihury «nd W.S. Ramantur thy, «P0, Ann. Rapoct, 8ARC (1973).
4. Z. Praenkal, Phy». Raw. 15£, 12B3 (1967).
3 . Sciaajon Configuration in tluaternarv Fiaaion (S.K. Kataria)
Tha phantmenon of qufttsrnary f iaaion, naaely tha ««laaion of two
l ight charged part icles, has baan obaarvad recently for tha caeas of235 2&2 1
tharaal fiMlon of If and apontanaoua riaaion of Cf. Tha axperi-
mantal result* wera obtained for enargy apactra of tritona and alpha
20
10-
H_______—\\\
2
3
1\
90" 180
f ig .3. ) Tlio obi'tiru.id mbiio uneryies or Uqhl t lu iq^d purl lcleu
i n qudturnury f iss iun aa a Functtoo of anqiti b^tueffn th«
t)lrt?r.t ton of motion of t«c l iyht clinryml p:<r(leJns. The
r.rt icii j .-it,*Sil (Joponcio CHy o( niu;*n Mritarji**©' under dirfnr«nt
h/ptiihcag& ..irfl also shuwn tiy i:ijrue6 1 ~1 .
-51-
partlclee in quart e m ary riseion. Tha energy and angular eorrelatione
.between tha two light chargad partic laa in quarternary riaaion ehown in
figure*, have provided detailed information about aciaaion configuration
of tha aciaaioning nucleua.
Varioua hypothaeea regarding initial oonditiona of tha two alpha
particlaa at aciaalon, have been taatad againat obaerved data on anargy
and angular correlation with tha help of trajectory calculationa for
20\
3
^ 2
^
\\
i I ^L T I i I
10 20
fig.J.2 thy obturvsd •.«„ on«r9r o^ ons a l p t l , p , r U c l , „ .
ts2Clr°H.Of. th ' """^ o f " c c n d * l p t " P«r"cl . and!"V i " '«J»ctory c. lcul . t ion. undar th .
v»rlou» h|rf>oth<ja»i shown by curvus t -« .
- 5 2 -
quarternary f iaaion. for thaae calculation >,e have used the fallow-
ing «.t of variable*! (1 ) The dlatance between the two fiaaion f rag-
wente, (2) The i n i t i a l s>nor9i»a or two fiaaion fragawnte, (3) Tha
space and *oo*fttu« co~ordin«ta# of two UP at th» t i » . of their Mlsalon
and (4) Th8 time of aaiaaion of t«o LCP after »oieaion. THe diffarant
hypothsaaa. sake different aaau«ptiona rogardinfl (3) and ( 4 ) . Tha
w*lue» tif othsr uariablaa hawe bean kept conatant under a l l hypothaaaa.
Tha wutual fores between th« two LCP it, a f the «««« order aa tha
effective force doa to fisaion fraQiiante. Therefore tha preeence of
one alpha particle Oreatly influencaa tha action of the second alpha
part ic le in the v ic in i ty . Fortunately t h - etrong «vjtual r«pu leion,
reetr icta the choice of the c r i t i c a l conditiona of U P at aciaaion. The
trajsctory calculationa ware carried out under four hypotheeea and c a l -
culated reaulta arc ahown in figuree1 ^"f igur»a3. I -3 .^;The hypothaaia
Thy oba«rued ftnyul^t corrulatiun of two light chargedparticlws in i(u«ternary fission vnd tha conputod angu-lar corruldtiun unaat four ditfttrwnt hypothasos forI n i t i a l cundltiont) of iCf «t sciaaiun Shown by curvaa1-4.
-53-
4, which fits the data aaaumea that tha two l.CP ata produced naar tha
tips of fragments independent of Bach othar with a mean Ufa of 1 0 ~ 2 1 S S O .
Tlis major *sis of fragments make an angle of tS* with reapact to ths axle
or aeparation of fisaion fragnanta. With thaaa prascriptiona, tha two
i-CP iii producad at diffsrsnt tias after scission which result* in very
much reduced mutual rspuleion and consequently raauita in no snargy corre-
lation E (t ). Also the two LCP are producad almost on the sams aida
of aeparation axle resulting in enhanced yield at smaller anglea. Tha
values of initial parameters oan not be determined unambiguoualy, though
tha essential foaturea of LCP amiaaion hove bnan brought out.
1. S.K. K.tetla, Ph.D. theaia (1975). Bombay Hniversity
4 . flaeioo frapjaent <ma AjpTia Particle Energy Correlation* in tha
Thermal Nautron Induced Fisalon of U (D.M. Msdkarni, H.K.
Choudhury, S.R.S. flurthy, P*N. Rana Rao and S.S. Kapoor}
In the present uork, we have invaatigatad dsteiled energy and aasa
corralationa between the fission fragments and the Long range alpha
particlaa (LRA). Also unlike in aoet of the previous investigetlon*
the LRA uera datucted at all anglaa with respect to the fission fragment
direction in the preaent experiment, ao that any biasing of ths energy
data due to energy angle correlations la not preaent.
A gridded jack-to-beck lonisation chamber was used for tha detec-
tion of fission fragments. Tha cathoda of the chamber contained a thin
235 2VYNS film on which a thin aource of U («/ 1 cm area) was alactroapreyad.
-54-
Th» ehambBT wo« tlllBtt with a »ixture of arson (97J() and mathana (3jt)
to • praaaurs of about 1.5 atmosphere*. The collector plataa had thin
»luiiiniu« window* and thick ••nlconductor detectors were mounted cloaa to
tha*« liuwiniurs *indow» for the dataction of lHA. The LRA detactora wera
• nvt'Oy calibcatad with natural alpha sources. The pulas» froai tha tuo
1400
1200£ 1000§ 800Ou 600
400
200
-
-
jr
J
. . . BINARY.. . LRA
(b)
1 • *• • ,
a » _
1200
1000
i\ 80U
' ' 600o
^e,0 160 180 200TOTAL KINETIC ENERGY ET (MeV)
LRA(a)
AGO:
_L120 140 160 180 200
TOTAL FRAGMENT K.E. BK(M?V)
r i « .4 .1 i») rr.gmunt (.inotiu «noru> aupcLrum in LH« flsaiar,(b ; TnUi kinetic unurgy sp ocu« in bmarv 8nd LRM
-55-
£ 180w
w 170
150
o * . * .
oo o BINARY (... LRA .|
i
1.0 12 '•« . 1.6 1.8
FRAGMENT MASS RATIO
20.(1-
rOO- i i
J_1.0 1.2 M 1.6 i H
FRAGMENT MASS RATJO
r i g . 4 . 2 ( a ) Ho«t ptobablu ualuo* or t o t a l k ina>; . ..binary and LHA f l ua lon <• a funct ion in raratio.(b) ilunddrd duvlatlun8 or tha total ki.--..{.jdintributiona In LH<* fiaalon as a runcl.-•aaa ratio.
j2 0
i I-
- 5 6 -
collactora of tha ion cHanoir and tha twoj.fi* datactcra, gatad by tha
ooiricldanoa output or ona of tha grid pulaaa and tha LRA pulaea, warn
racerdsd on Magnetic tapa with tha four paraaeta? data acquiaition ayataau
8in«cy evoota w»rs elao racord»d at tha aa«« tins for on-iina cal ibrat ion.
Th« ospariwsnt waa carried out in th« n«ut?on baai* of CIHUS raactor with
a neutron tlux of 3 x 10 n / c » V " c «nd a total of 3.6 x 10* LH* avsntaG
and . 5 x 1 0 binary avanta wara racordad.
Tha data wara analyaad in a CDC-36Q0 co«putar. Tha aaaaurad LRA
•nartty Ma* corracted for anargy loaa in tha gaa and tha thin aliMlniua)
window. The tJM fiatiion fraowwnt pulaaa war a calibratad by tha binary
> •
g•zhi
klO(X
in
£
•
.0
I
i
12
I1 * {i I i
1.4 1.6FRAGMENT MASS
IL
1 I Ii i I
1.8 2.0RATIO
f i g . 4 . ^ Muyt ptalmbla viiiutjs uf LR* unurgyftdymjnt »«sa r a t i o ,
function of
f i s s i o n fragment data using the ua-lu<;a <:f Scninit t Hi <sl f o r the u s k
onergiee. In tha present geometry, the LHfl f iasion fragments suffer
more energy loss compared t o b i na ry ewanta, and nones tha H g h t snc<
heavy peaks were c o r r e c t e d for fchia ox tea energy less (cbcut 2.1 £ 0.1
end 2 .2 • 0.1 MeV for l i g h t and heavy f i-agmant-. paaka r e s p e c t ' uf-... y } .
fig43(«) «nd 1(b) ahow tho fragment kinatir. i-n^ryy (t = £L + LH) and
total kinetic energy ( £ , - £. + E ) opoctre, along with fragment, kine-
tic energy spectrum in binary f ioaion in f i.cj-L':'1o). I t io sown ;;-iat
the total kinetic energy spectra in birtaty and I.KA f iss ion nri, •; •". '
similar except that on the average about .3 hie;' mure energy is r ;., jr.ucd
In L"A fission. Table I summarizes res.j l t i ' of a i l the average telype
of th« energiea of th» fission fragments and of the LRA, The sassas of
the fistlon fragnente were obtained both in binary and LSI 'iJflicjnn by
invoking Monentum - maes conservation re lat ions. The dsta wars emaiyoed
to obtain the total kinetic energy distr ibut ions i,rt binary end IRfl
fiacions for different wass rst ioB. in ' iy/i^51ha mast probable veiuea
of th» total kinetic energy distribution!) in bimx-y end LHA f iss ion and
standard deviations in LRA fiBtiio,-; a.a showti as a function of fragment
mass ratio. I t le seen that near thi- eynmetric mode of mass niv l t ior .
the total kinatic energies in binary and LHA fi&Dion are nearly S.~\V,G and
the ktidtha of the LRA total kinetic energy distr ibut ions see wsiy large
in eymmatric modes as compared to th<-'l; for the asymmutty modue-.
The most probable values of the LftA Gnorgiea as a function :>T maee
ratio are plotted in F ig .43 . I t is aoen that the avaraga LRA enargy
remains constant over a very wide fanye of mass divisions except in the
vary symmstric nodes where i t is seen to t>a larasr by about 2 ftsir.
252Similar results were obtained earlier in the opont?neoua f iss ion of Cf
Heavy ^HFragaantCnatgy £H
Light KLFragaanttnergy £,_
Total tFragaant _tnorgy £
Total £KineticLnargy Ej
Alpha C^Particle _Energy E
a. Saa Raf.2.
PreaantLRA (n«V)
63.S+C.3
90.2+0.2
6.9+0.1
155.4+0.5
10.8+0.2
171.3+0.5
11.4+_0.2
16.8+0.5
4.1+_0.4
mac<Binary (r«eV)
69.1+0.2
8.3+.0.1
99.1+0.2
5.1+0.1
166.7+0.5
10.8+0.2
168.7+0.5
10.8+0.2
:
Cazit 9tt«M »t 90#(PteW)
W>.77+0.15
6.4+0.02
92.32+0.10
4*47+0.02
157.46+0.4
8.74+0.02
15.8+0.2
4.5+0.2
Binary (fla«)
69.91+0.13
8.0+.0.02
100.42+0.10
4.66+0.02
168.55+0.04
9.88+0.02
• •
-
03
MOST PROBABLE FRAGMENT K. E.<MeV)
3 O
a S
^ =t
mzm3DQ
o
t b2 3
r?
m33o
rn
-60-
•nd u«ra intarpratad In terms of the dunbbell modal of Whataton* where
the alpha particle awittod vary naar tha Iwavy fragMant in tha symna-
tr lc ««sa division gains nora anargy froM tha coulowb f ie ld.
130 140 150 160 170 160
FRAGMENT K.E.,Eh(MaV)
130 140 150 160 170 160
FRAGMET K.E.,Ek(M«V)
FiB>4.S flo»t prsBJibis valus* of LH4 umrgy as a function ofr u g w n t kinetic >naryy for variott« ">as» div is ion* .
- 6 1 -
Various correlations between the flsaion fragment and LRA energies
ware obtained for apecifiad mass ratios. In Fig.4$ the moat probable
value* of the total fragment kinetic energy (Xu) ea a function of I.RA
energy are plotted for various mass ratioa. The correlations are roughly
linear and the values of alopea ere given in ths f igure. I t la seen
that the slope dtk /dEMcraasea as tne mass asymmetry incresaes, whioh
la opposite to that obtained by flehta at a l for the caee of Spontaneous
252flaaion of Cf. Another correlation is the variation of the most
probable IRA energy with fragment kinetic energy uhich ia plotted in
Fig.4£for various masg rat ioa. This correlation seems to be non-linear
and is very important from thn noint of trajectory calculations.
Above results offer an extensive aat of data on the energetics of
i-RA r ins ion for any theoretical atuuy or I.HA fiaaion and w i l l ba complete
i f the information on the angle of LRA with respect to fragment direction
is also obtained. Further experimental work ia in progress to yet this
information by the abova mithod using gridded ion chambers.
t . H.W. Schmitt, J.H. Nailer, F.O. Walter and A. Chatham-Strode,Phya. Rev. Letters J_, 427 (1962).
2. Y. Gazit, A. Kataaa, C. 8ei»-0avid and A. lor eh, Phya. Raw. C4,223 (1971).
3. G.K. Rehta, 3. Pol ton, M.Ribrag ar>d C. Signaribiaux, Phya. Rev.£7, 373 (1973).
-63-
0 . SOLID STATE PHVSICS
I . WIUTROH QimthCllQH STUDIES Of HAGME.TIC HATEBXALS
1 • Nonaoharlcal Magnetic rfrmant in MnAlGe (S.K. ParsnJpB,
S.R. Tendulkar*, L. Hadhav Rao, N-S. Saty* Nhjrthy end 8.S.
Srinivasan)
1The ternary compound MnAIGs has been atudisd using polarised
neutrona for magnetic moment density investigation. The structure
deteraination has already been reported.
For polarised neutron studies a single crystal epsciisan
aligned for / " 0 0 1 J ZOna wae usad. The polarisation ra t io * ware
measured for re f lect ion* in this 2one upto ainS/^<vQ.9 A . timgna-
t i c structure factors were obtained from thsse polarisation « e t i o * s f t w
taking into account the instrunental corrections l i ke th» inconplete
incident neutron polarisation, inooa)pit>ta fl ippinfl of neutrons end
also the extinction affects in tha aaJiple. The **enetic structure
factors thus obtained are plotted in F i g . 1 . 1 .
These Magnetic structure factors ware an«ly«ad on t h * b«sis of
a fra*-«tom-l ike d-orb i ta ls , for the PVi atom, modifisd by the c r y
s ta i l ina f i e l d . Tha site ayametry of ths !*s* atca i " tutrahadral
with a tetragonal f i e ld provided by Al and Ge atons. This tetragonal
f i a l d sp l i ts the d-orbitale into four symmetry o rb i ta l * of type
* i 9 ( d . 2 ) i B i 9 l dx 2 « i h E 9 ( d « ' d y i ) a n d B i B ( d x y ) . Following
and Fraaeiah fornalisn tha Magnetic atructurs .factor* K.^,, have boim
axpreased in ter»s of the sphsrical Bessel transfor«« of 3d Hartre*-
Fock rad ia l wav* function*, ^ J S yland th* «n Magnetic *OM*nt « * ,
• Research associate froM tha University of Bombay.
- 6 4 -
2 / * < J 0 >
where 6 = 'V
with W V ^an fractional orb i ta l populations af the unpaired electrons in tha
respective crystal f l u id luvels and
D h k l
U , = 15/a sin/5 Cos4t^ where J$ i s tn# angl«
between scattering vector hkl and the tetragonal axis and
cos 4«<- (h*+k4-6hV)/(h2+k2)2
The obserwBd magnetic structure factors wars least square* f i t ted
to eqn.(1) using th* y*J y X appronri^te to Nn , fln and fin + confi-4
gurations and withH,€, £ and (B. -8 ) as variable parameters. Tha
principal outcome of this analysis is,
(a) Tnw magnetic moment of the Pin atom is 1.45^g,which is 3.5^
nighur than the saturstisn magnetization value. Houevsr, on the
basis of this zonal data alone it is difficult to argue that this
differencu is due to the negative conduction electron polarisation of
0.0'j M-g /atom.
(b) Tha fractional occupancies of the crystal field levels are,
A1 » 0.38, B1 =• 0.31, B2 - 0.30 and E = 0.01.
Tho i*ia+a i i function which correspond to e function of cubic
f i e l d , contain 69> of the unpairad electrons. Thus the nonaph*rical
-65-
nuLufe tJ obvious. itnutner etrikiny I'eatura is. the presence of a
large fractional occupancy ut thu orbital A directerJ aiung the
, thy easy axis of mag/ieli2etioM. The absence
of any ligantl on thu babsi jjldne purhups explains thB alinoat aqual
population of the B. and B louels.
The structure factors* calculated with tho ut-'bt tit arw shown in
Fiij,'i.\ as a continuous linu through tho ualLulatud points.
Spheritally auuracjtd monti-nt density r P(r ) around f)n atom has
been ubtaintd by Fouriar inveraion of thu ainoothenad curue through tho
form factor. This is plotted in fig.1.2, uheru it has
0 01 0 2 0.3 0.1 05 0.1 0.7
0 01 O.J 03 <U 05 08 07 OP 09 10
r i i | . 1 . 1 Utjsiiruud Magnal lc Stcuc
factors (^ ) *hd Calculated
ruynntii. btructiitH FnKto'H
(continuous lino) with best
r i t .
Fig . l .Z . rtadial Momunt Uvnolty D i s t r i -bution or Hn in pliiRlCo atjdof nnl and Hnll in Pin Sb.
bi'r iu compared u/ i th i J ' l r J ^ r o u n d thu two inui,.j_-- >'.••• 'In "Lows i n an
i b u s u - u c l u i - n l compound Pln.Sb. Tht? cciui(jario...n :n-..'s t h d t the maynt i t i c
iiiuwfent d e n s i t y aruu i iJ fin i n iliiAJGo i s s l i g h t l y mere ' J i f f u s u than t h a t
around the twu Mn atoms i n Hn 5b.
1 . a . K . P a r a n j p e , S .K . T ^ n d u l k a r , L . Plddhau rtJ- arvj ?;•'•>> J a t y a f l u r t h y
(Jraraana, :5_, 3 b 5 , ( 1 9 V 4 ) .
2 . HhRC 7 6 8 , N u c l e a r P h y & i c s D i v i s i o n Annu3.' - i . - ^ u r t i . i g ? ^ } , p . 1 0 0 .
3 . K . J . i iJbi^s and A . 3 . F r ^ e i n a n , J - P h y & . CNiim. i j ^ i i ; . - : , 2 £ f ^ * ' ( 1 9 B 9 ) .
ii . M.t. Watson and A . O . f r o B . n a n , A c t a C r y s t . _« ; . .'•'? ; , 1 3 & 1 } .
5= K. s h i b a t a , H. W a t a n a b t i , H» Vamaucn i J«.Td 1 ' a n i m . ' h & r a3. P h y a . b o c . 3 a p . 35_, <i^d ( 1 9 7 3 ; .
6 . 3 j H , W a r n i c k , S . C . H a r z k o and W . 3 , Rorf:n(iuus .", - i p o l . P h y S . 3 ^ ,
249S ( 1 9 o 1 ) .
7 . H . A . A l p a r l n , P r i u a t u c o m m u n i c d t i a n .
S-Ufef "0. 5 t u d v ° f Magnetite (W.C. «sl<hech*3f
Ro Chakrawarty t t- • Wadhau Rao and M.S. i;si:v,i
neutron sfcudiaa of alngis crystai spsctwens of
e.jO^ (rsagnatito) had been mada eari ies: ' . ^3304 i a *
f'urriiBDgnetlcally orcieretl compound of invorms arjirsei structure in
which the egsgnstis ians occupy two kinda of eii.u» *A srtd 8) . Th«
/i"»alts~ heus a t etttsl'iodral and tho 8-8 i t en ar< uctuh^di'-;! cocrdin*-
6ion to tho oxygens and the magnatic moments on thsi3 stsa arit.ip*rallal<
The previous analysis use mada on the baais of rv&z ico vQluaa far
A ami B flit a *omsnt3f namaly Fe3+ on ths K-.S;U\JG t,-,d » random
diatsibufcio.i of Fe end Fm on tha B^aitea. The A-sita form factor
sas found to b« auch sharper than tha fpne Aon fa"1* ?i,r« factor c « l -
culated with Hartree Fock uavefunctions , Kuny B^^its fcrin fsctora,
particularly for tha low engln reflection* w«rt found to daviata
algnificantly fro* tha average curve. Thaaa faaturea required
further invaatigation and/or possible altarnatiwa intarpratation.
Fresh Measurements have been ttsda on a thlnnar cryatal orien-
tad in /"1 10_7 sone for reflection* with ain S / ^ upto about
Q..6A . Tha particular cryatal geometry facilitate many four fold
raflections to have different path length*, thua providing a meane
to (..hack relative extinction for the cryotellographically, equivalent
reflection*. Perceptible difference* {--^2%} in tha polarisation
ratios were obsarved only for tha equivalent (444) reflection* whose
path lengths differed approximately by a factor of two. Though (400)
ia expected to show an even larger effect it cannot be examined in
^/iiOyzone bsceuss it is only a two fold reflection. Polarisation
ratios were alao neaeured aa a function of aiaaet fro* the Sragg
u.-IwffU-tior; tor (444) and (331} reflection* and the ratio* in these
cases wart found to reatain unchanged within the experimental error.
These obsarvatione indicate that tha extinction ia aecondary of
typa I or/and priatary.
Additional m*«*ur*ment» were Made to get better estimate* of
nuclear parameters ae these in turn affect the values of Magnetic
structure anplitudes. Unpolarised neutron integrated Bragg intensity
•easuremsnts were MSda ( A • 1*24 A) on a aingle cryatal epsclaan
in' ^"nyxone. Mainly for oxygen v~ -parastater sensitive reflections
Sfcoichioaetry of the saaplss was sacertainsd froa gravlnetric
analysis. X-ray fluoreecence and spsctroecopic anslysee wars Mad* tp
sstiwata tha SMOunt of iapuritlss. A nuMbsr of dspolarisstion
ae»»ur«r.«nts «*ra mads to enable r«liable dspolarisation correction
for the data. X / 2 contamination of the beam has aignificant eTfect
on «o»a naiBuri»«ntl and ha. been roughly accounted for in the enelyais
(on tha b««i» of 1* contamination).
i i r 4 ff f i l it Ti II I i
(11 ' 07 O.i 04 "05 06 07 - G«~ OS
Hujnutlc form fact.ura in Fn 0 .J 4
*-1
rt««»ur«««nt» bayond tin B/X 0.6 A ar« in prograsa. Soaa
tantatlua conclualona hav« ••urged from the analysla of tha data
obtalnod so far. A conaiderabla raduction of tb* A - aita aoaant ovar
ita frea Ion value la auggeated. Thara axiats houavar tha poaalbility
of additional aptaad out «o«ant which is not aaaipled by tho taaaurad
Bragg raflactions. Tha fora factor* for A and 8-alta •onanta obtalnod
in tho analysia ara ahown in fig.2.1. An avaragad A-«ita for* factor
curva has hean uaad for calculating B-aita for« factora fro« raflactions
ii*»ing contribution froa) both A and 8 sitaa (A8-typa raflactiona).
-69-
value* of 3.7 and 4.23Jf-n hauu respectively beon used for
the A and 8 sites. For comparison the free ion form factor
curves for Fe and Fe ions are also 3hown. There exist signi-
ficant fluctuations in the 8-sita form factor values which are yet
to ba accounted for. However the B-sita average form factor doaa
not seam to differ much from its theoretical counterpart. The
apparently lower value of form factor for the A-site reflection
(220) ie presumed to be due to multiple Bragg effect.
1. R. Srinlwsasn, V.C. Rskheche, S.K. Parsnjpe, H.O. Begum,L. Kadhav Rao and N.S>. Satya flurthy, Proceedings of InternationalConferenca on MagnBtism, Hoscou, Vol. IV, p. 246 (1973).
• \
2. R.t. Watson, A.J. Freeman, Act a Cryst. U_, 27 (1961).
3. Neuttgn OlffrBCtion Study of PolvcrysfcalllnB TbAg a t
and at 90°K (S.K. ParanJpB and R.3. Baguni)
An alloy of TbAg Mat prepared by aelting equiatonic portions
of Tb *nd Afl in • Mttar coolad Cu boat uaing an arc furnace. Tha
X-ray diffraction pattern of tha alloy revealed that tha alloy ia
of single phaae b*c.c> structure with a unit call aize of 3.622+_
* 1 )0.003 A which la in good agreement with tha earlier work. '
Tha room temperature neutron diffraction pattern consists of
purely nuclear reflections cheraetarlatic of a b.c.c. structure.
However, no conclusion cen be drawn regarding ordering aaongat Tb
and Ag atoms because of their cloes nuclaar acatterlng aaplitudaa.
• 2Tha Qsbye-Ualler factor, B, waa detsrained to be 2.5 A . The 90*K
pet tern revealed a number of euperiattice reflections which could
be indexed en. the basis of a tetragonal unit call doubled along two
-70-
Cube edges. Th« antiforromugnutic structure is of C type in which
the Momenta in adjacent ferromagnetic (110) layers are Aligned
oppooitely, parallel end antlp«r«llel to the z-axls. An ordured
C»C1 structure* w«a indicated by the presence of Magnetic raflectiona
like (111) and their intsnsiti»« showed that the ordering of Tb and
A-2 afco1** uati aonpl«ta» Since the structure factors of ali tha
r»flectione iti tha taxa, their lnt«nsitiaa yield tha form factor
straightaway. Tho curve waa normaliaed at — — » m 0.1 to tha theore-ms
tical lb foi-ra factor curve* obtained by Traanan and Wataon ' '
uaing non-relatlvistic HsrttBB-fock wave function* and by a fully
raj.ativlst.ic mixBd ovnTi^uration Dirac-Tock calculation. This
normalisation led to a magnetic mom ant of 4.3£U.2f*' per Tb atoN.
Fig.3.1 thoua the comparison of the present form factor with tha
\
THKOHFTICM. HAn
IHftlKf Ilf.At. BElA
• E*Pf ClMfNTAt. TbAg
*\
02
01
0 I L 1 I 1 L . . I L
0 0.1 02 0.3 01. 0 5 0.6 0.7 0» 0.90 »
l i g . 3 . 1 U'.ntiariiiDn of thn n<pnr 1 munta 1 Tb farm I actur In ThAgwitr^i ' / a r lnue Tb * form f a c t o r s .
t hfoorulicul curutiS as u/tll as witli the exp-r imental Tb form
4 )factor . ^ayn.itiiiaLion dunbity in TtWtg soemS tu OB more uxpandoU
- 7 1 -
i »1 at iwe to tha i in Tb'
Tha tumpurotuis. d'^tnuyncf <af t in' v, 7 1C J ind(,nati= pu jk yislduU
a Niibi tuiipuratura uf u '
1 . J . U . C a b l e , W . C . K o a h l f w a n d £ . 0 . WoJUan, P h y a . Haw. 1 3 6 A . 2 4 0 ( 1 9 6 4 ) .
2. A , J , fras.-nan and H .i.. Uataon, Phya. Rev. 127. 2058 (1962).
3. ."!. Blums, A . J . Fresman and H.E. Watson, J . Chem. Phys. 37, 1245(1962)} J . Chera. Phys, 41_, 1674 (1964).
4 . C.W. i.arjder, T.O. Brun, J .P. Dgaclaux and A.3. Freeman, Phys. Haw.flj*. 3237 (1973). ' Y
4. K Hnutron Diffraction Study uf Co-dupad YbraQ^. (b.K. Paranjpe
and P •>'•
i s a canted sr .parromdgnet with an indopGnde^^ ordering
e?f tha I ran and the ra re -s rc th momanta. I t has a compe: aation po in t ,
3ta tsmpurature induced spin reoriantation transitiun and contains fe
ions in octahedral Bites only.
tile have used u single crystal specimen uf YbFeO, doped with 9X-o
of cobalt for collectiny data. Such dupinys may ghanye the atomic
co-ordinate* <JS wull as the magnetic charactaristica. VbTeO has an
orthorhombically distorted psrovakita structure oulonging tu the space
group £>, . The unit cell contains 4 distorted perovskits units with
the fullowiig atom positions:
fe at M b ) Ql/20
Vb and at 4 ( c ] +(xy'/», >/2-x 'A+y 4 /3 )Oxygen I
Uxygun II at 6(d) +(xyz, t/fe+x 1/2-y
X y 1/Z + z, 1/2-x ^
-72-
Intensities of 140 i of LUL ticius (<<o iaaup-ndtnt ) (uve b..'un mtsa—
sored at room tumpuraturu in thu ^/ UU1 __/ zoiiti which do not contain
ant if •irrum-ignatic ref lect ions. Thusu intensi t ies, after oaing
currected tor absorption, haua UHUII uaud in Die rieterflinution of the
atomic coordinates by the ieast-squares refinement technique. I n i t i a l
2uaiues of th« coordinates wert! takun from Claruzio «t
rusuit.8 are :,houri buiou:
The
factor
Yb "V
InitAal
.er 0
U0
.0
.98064
.07076
0
00
f inal
.<»00+_0.
•9794+u
•ovueTu
056
.0008
.U
Yb
Oxygen I
Oxygtn 11 yz
factor
Initial
0.U
0.900640.07076
0.11690.4537
0.6866
0.0S99
0.4U0+0.056
0.9794^0.0008U.0708+.U.UU07
Q.11GB+p.UU2J
0.6890+0.U0160.307570.0020
not var iud
Jata collection on both tht- maQnetic and nuzluar redactions is
in plugifos in ths ^C'0_/ »ons.
1. U.C. Koehler, t . U . u/ollan and n.K. Uilkineon, Phys. Rev. 118.5B (I960).
2. n. Harezio, J.P. Remeika and P.0* Dernier, Acta Cryst. B26.2008 (1970).
-73-
I j , MLUTHUN INELA5T1C SCATTERING ftMJ UYNAMICEi OF CU OE1M5EH WLDIA
'• Lib rational flades uf kJatui ffaiecuios in SeiiQ .4il, o^. (C.L. Ihaper,
T. Sriniuasan and P.K. lyengar)
The frequencies of libratiunal modus of water iiiolfjculus in a
einylu crystal of Be30. .4H,U have bt-en measured aL 12U°K using the
filter-delfcclor spectrometer. Thesj studies, wnich employ the polari-
zation dependence of tha nautron incoharant inelastic scattering cross-
soution aru useful in underatanuing the hydrogen bonding in crystal
hydrates.
The structure of BeSO.4H_G is tetrahedrai with a spacu group
2I4c2. The four water molecules in tha crystallographic unit cell are
related by four-fold rotacion about the c-axis of thd crystal and thei
angle £ that the plane of tha uatur molecule makes with ths a-b plane
of tho crystal is about 17°. If ths crystal is aligned uiith its c-axis
in the t-catttiring ^ilanu, then tne intensity I of tha inelastically
scatturucl neutrons for Q purpendicular or parailui to the c-axis i6
givan by
0 f here, re fers to the nautron wavb woctor t rans fer and I and I-- i o
to tha intensity curret>ponding to in-plane and out-of-plane modes of tho
water molecules respectively. The contribution of in-plane and uut-of-
plana modes can, thus, be predominantly separated by suitably orienting
the crystal.
Tha neutron inelastic spuctra from 1 c.c. volume of the crystal are
shown in Fig.1.1a and 1.1b. Measurements mare also performed wrth trta
- 7 4 -
ilfiOl t
a i
_) 1 L ...
SINGLEi, 0 11 c
t.HfiCKY'IALC - O ' l «
» ! - — — • • • ^
4H,0CflVSTAl-0»l«
(a)
I 1 L_
( h )
.1 _... J I t . . L 1 I I
4. IHfl
1Ja;1' rt
<uVI
_.t
1
/ \ POWOKR
V., _ . _ / •1 J i 1 _i I i
BeSQL. ^0?O
POVVOF^R
1 1 I 1 1 1 1
( c l
r j
( d )
- * * • * - ! • , .
\f 15" 17° 19" ?TMONOCMROMATOR ANGLE [ C u ( l l t ) j
J 1 L i U»00 600 50(1 .'.00
FMF'ROV IDANSFf.M | r u ' ' |
f j y . 1 . 1 K u u t i n n ir i t iJ-<!>> i r b p i > ( . L l . i f r m Mu ' iU - 4 H ^
J i m j l " t r y b t - i l ml:-l!»>ir " . m - i ' i 1. 3 t « n t l ? O ° l i
31 lull"!',.
JniJ l)^ . t ) 0 .ur il i l l«
cryGt<ii aligned with i ts c-axis ptirpendicular to the scattering plane
and spectra similar to fig.1.1a ware obtained Tht* spectra From powder
80SO. .4KLU aria i ts dscteirated salt are alao shown in the f igure.
Table I cjives a summary of our results along with the assiynmente or
the observed frequencies* Comparison u/ith optical data and theora-
t i ca i calculation ic also included in the table.
To sum up, our exparimentai data show that the in-plana modoa in
Ba304.4H20 hawe a frequency of 715 cm"1, while the out-of-plane modes
are centred around 70B cm . These modes could tia ruaolvad because of
their polarisation dependence which uias not possible in the powder
sample. Ths widths of the l ibrat ional peaks ?• largar than thu
- 7 5 -
and...c.ali-u,iale<j f i-eQuam;ifeS ai;?. their assiqnmants
Work
Noutron
y II c
uptical
Frequencies in Cm"'in8ubU, .Ari2U B9SU4.4Lj.;U
92S(C) 71b^R) 347(1)
708(U,T)
900(C) 709(L) 356(1) 696(?)
665-760(iU) 317(R) 436-5^^ (W) 311 (R )
ThBoretical
1035(R)
1O65(T)
(C) = Combination of librational and lou frequency lattice mode,•(l) = lattice mods, (fl) = Rocking, (U) B UJaying, (T) = Twisting(LJ = Ubrational (R+W+T), (?) = incontpletp dsuteration.
.. <OJri-Tidntol resolution J-6C cm"1 ) . The optical measurements are
;,-, reeaonaole agreemant aa far as the waving modb is concernsd but
not with raapect to the rocking mode (twisting is infrared
inactive). The calculated frequencies, based on the modifiad Lippin-
c, t sohroeder potential function for tha hydtocjan bond, ace roughly
the same fcr all the modes as also found experimentally. Tha large
discrepancy in the actual magnitude of the two seems to suggest that
9ither the force oonotant parameter* of tha potential function at"
different for a polar crystal like BeSO^.^H u or a diffsrent potential
-76-
furiction is called for.
•Work performed under Research Contract No.1i02/HB or tha Interna-tional Atomic Energy Agency, Vienna.
1. C.L. Thaper, 6.A. Dasannacharya, A. Sequeira and P.K. IyengarSolid State Commun. 8,, 4 97 (1970).
2. 5.K. Sikka and «. Chidambaram, Acta Cryst. 825. 310 (1969).
3, P. 'Jiaoi. K.H, Halluege, 3« Jager, G. Schaack and F.3. Schsdenia,Phya. Kcndane Plat«rAe T.t 52 )
4. A. Saquaira, Ph.D. thesit, Bombay Univbrsity (1970).
2. Nuutrop Inalastic Scattering from (NH^ )2SQ4 and the Mixad
Salte of CtttH, ) K ,7-SO.. (A.H. Venkatesh, C.L. Thapor
and K.R. Rao)
With a view to studyiny thu dynamics of NH ions in C ^ ) , 5 " * a n d
in thB mixed salts of <r"(NH4)x
Ki_ -^2StI4 ^ i n w h i c h t h e N H4 l o n * are
intrt-L :.fd in i' iiost lattice of K2S(J4 t o l'ePlace sor.e of the K ions
randomly), a suries of Bxperi.Tients have been carried out on the
fiit detector spoctromdter. Two values of the concentration
parameter x wore chosen, namjly u.16 and 0.5.
The neutron inelastic spectra wera ootained in the ruyion
200-1100 cm by using a Cu(111 ) monochromator and 8e<Q filter analy-
ser. Suitable thicknesses of the samples :uere chosen in order to
have reasonable scattered intensities. The measurements were mainly
done at a scattering angle of 90° for sample temperatures of 300BK
and 110°K. A feu spectra mere also recorded at a scattering angle
of 75° and these were found to be consistent with the 90° data. In
order to check on the peaks arisiny due to elastically scattered
-77-
neutions passing through tha filter, the measurements warn made with-
out the filter also.
Some •/ tha experimental observations corrected only for room
background are shown in rig.2.1.
Tha roam temperature spectrum from (NH^^SQ^ (Fig.2.1a) shows
three broad peaks around 600, 350 and 270 cm"1. Except for the last
peak these ualuss are in reasonable agreement with thB values of £30,
340 and 235 cm reported by Sakamoto et al from a similar instru-
ment. The cold neutron timg-of-flight experiments of ftuah et al2
i:
8.i.
—r--T- -r—1<W <NH,),M*
r-jixrri
•.€-•0'
ii u » t? S itMOMOCHROMAtOK ANOLC (OCO)
• i * i i i ' I I IMM *M W W» «U MO
rwflOV TRAHSFf PT (ein >
Fig.2 .1 lnnlosl ic lncoh»runt neutron spectra from (NH. ) 2S " 4
a " d »'»od
salts 2 " ( " H A ' K I ^2tiUA U i t h " "* °"16 *n d * "' ' 8 8 ° tB><t
for dKtaiisV ""
do not aes the peak around 600 cm" and they report the values of
305 cat* (with a shoulder on the ioJsr frequency aidu) at 296°K and
335 and 200 cm" at 172°K. The results of Dahlborg et a l are
raportad to ba in agreement with those of ftish at a l . So, the'a la~1a disagraamant as far aa our peak at 270 cm is concerned.
-78-
A dramatic change in the shape of the peak at 350 cm takes
placs at 110°K (Fig.2.1b). This peak, uhich is believed to be tor-
•ionul, splits intu two wall resolv/ed peaks at 430 and 390 e»~
and shoulders around 370 and 330 cm** . These raeaeuremanta were also
confirmed with (200) plane of the Cu monochromator, which provided
somewhat batter resolution.
The low temperature spectrum of the mixed salt (Fig.2.1c) shows
another interesting feature. The peak poaitione in this casa are
nearly the same as in the case of pure (NH i,5*0* (Fig»2.1b) but their
intensities are considerably altered. The spectrum for the mixed
salt with x » 0.S (Fig.2.1d) is more or less similar to that with
x v 0.16. The variation of intensity with concentration has been
observod in the A ( 1 0 5 cm" ) in Raman scattering experiments
on mixed crystals of (NH^)Cl Br . Similar studies hawa not been
reported '-n th- liijraLicnal mode.
1. n. Sakamoto, n. lizumi and H. lotohashi, OALHl-n 5033
2. J.J. Runh sr.d (-1- Taylor, inalnscic Scattering of Neutrons,IAEA (tfianna) Vol.11, 333 (1965).
3. U. Dahlborg, K.E. Larsson and C. Pirkraajer, Physics 4£, 1 (1970).
4. W. Bcuhofar, L. Ganzsl, C.H. Perry and I.R» Oahn, Phys. Stst.Sol (b) £3, 385 (1974).
-79-
3. Reoylaptat J,Lip9l notion of Ammonium Ions in (NH )jj
{jLlit^l 16J1 fl4\ 2 ^ j - (p*s> Goyai, P.P. Chandra, B.A. Oaaanna-
charya, K.H. Kao and C.L. Thaper)
In an eerlier work we had reported the neutron quasialoatic
scattering measurements from ammonium sulphate at room temperature.
l 2The measurements haws now been extended to .nixed salt 1 (KH } K JJ 4 '.16 .84 J
SO^ for the waue-wector transfer (Q) in tha range of O.j-2.1A~ . The
regiona of Q, whgre coherent effects atp important, lueta auoidcd*
Typical spectrum of neutron* quasialastically ecattured at an ar.gle r»
75" from the mixed salt are ehown in Fig.3.1, The daahed iine shows
inatrumentai resolution function. As in (NH )7^>0 we obaerue that in
H4^.16K 84 I 2S°4 B l s o t h B r B i 8 broadaning of elastic peak arisingJ +
(jecauoe of reoriuntational motion of NH. .4
The data heue bean analysed n'/ in tha case of (NH. LSO .
They haua been least square fitted to an expreseion of the following
st aach snt}lps 0t with ft(£l) ond X ao edjustablo parameters. The'bast
fit to tha spactrum at a scattering angle of 75* is Shown in Fio.^,1.
Fig.3.2a snd 3.2b show, with opan circles, the structure factor M(^t) ana
the characteristic ti«« X derived from tha fits. Alao shomn arc th«
results of •imilar fits to our old data on {NH ) S O . Th» characteristic
tlma as uelj a* tha structure-factor which is determined by
of the rotational notion are vary similar in the two
1. H.3. M m , P.b* Goyalt G. Venkataraman, 6.A. Daeannacharya andC.L. Thaper, Solid State Comm. £, 889 (1970).
to,
O-Tv
I - — • J - •-
O-2SI
0050
V KATTMtD HfUTHOMC [A*]S 5
5o
\ , i '
o i25 50 75
SCATTERINS AN6LE (CHMES)
100
Tig.3.1 fiHuiurad scattatsd nautton lnt«n«lty(.) is a function of wavalangth or'icittared nautrons. Th« d««hed Unais instrumental resolution function.The continuous lina (-) 1» th* .leastsquaru fit of tha »c«tt«rinij law totha naasucad tpactrua.
Fig .3.2
(a) Form factor »()j) as a function ofthe scattering anglt (/J). fiilf»dng
are forcircles are for 2"
8nd open
Tha characteristic time f , <• afunction of the scattering «ngJ"».rtllPd clrclse are Tor {»» Jjjfand tha opsn circles ara for
-81-
6,, Ammonium Ion Llhratians in Z (NH ) K. J JL.^\. .2H~Q Mixed
Crystals. (fl.L. Baneal, U .C. Sahni and A.P. Roy)
Dynamics of mixed crystals has attracted great interest recently,
both theoretK ally and experimentally, particularly using light sca-
ttering technique. Clost systems investigated till now involve sub-
stitution of atoms of one type with those of another in the process
"coreruing" thy total number of degrees of freedom. Little has been
donu to explore the effects of "varying" the number of degrees of
freedom in the mixed system. Hare we present some preliminary results
of one such study.
Potassium cupric chloride and ammonium cupric chloride ara iso-
14 2
structural (0,., two formula units prfr unit cell) and form mixed crystals,
/~( N H4) K. __72CuCl. .2H20, over a range of concentrations, 0.45 < x «£
0.72. The substitution of a K+ by an NH* bestows additional degrees
of freedom on the system. DUB to the high internal vibrational frequ-
encies (*v 1400 cm" ) of NH^, we may, to a first approximation, regard it
as a rigid cluster. Accordingly the present mixed system provides an
opportunity to study the effects of mixing on the libratione of NH in
crystals of quite high symmetry, i.e. D,. .
The mixBd Bingle crystals were grown by mixing the corresponding
solutions of pure substances and slowly evaporating the solution. The
composition of resulting crystals was ascertained by chemical analysis
and the crystal axss were determined by neutron diffraction fro* various
Bragg planes.
The Raman spectra were excited using a 600 mill Ar+ laser and analysed
using a Spex 1400 double monochromator with a spectral band pass of
: : . . « ; • • \.-<
i /
!
i ii
1!
i
i
I!Ii1
1l1
•'i
I 'M . I C | - ?'•
;
i !1/ i
Vi
Cl,. 2HjO
(b)" ' j i !
V.L..
Cu(NHt)jClv2H7O
I:
I i
.1 . _.. J.J
p l-lEl;l.'F.NCV (Ofn')
Flij.4.1
300 2M 20Q 1KfttQUENCV (Cm*'
US«K.
100
rig.4.2 lnt»n»lty variation or thi 183 cm* (a) and 199 ci»y () 9(b) paakt t>a a function or x. Th» x valusa Indicatedara Batud on chemlcai analyaia, • « 0.6 , howavac,la not ailowad as pnr literatura,?
-83-
1 cm The crystals uiure coolBd to allbv/iatu the considerable
broadening antm in tha return tompBraturu runs, Molarliaticn data word
recorded at B5°K for various concentrations. riy.4,1 shows the
for pure crystals. The curves in (a) and (o) ware* racoraed
by sending in and collecting t c scatterad liyht from difft>ront faces.
It is cltar from tha figure that tha wave number reyion 170 cm to
210 cm contains tha (nodes uihich arise out of the librational degraes
of freedom of NH . Tho positions of the pBaka atian in this region
correspond to 183 cm and 198 cm regpuctiualy. A careful study
shows th it the peak at 183 cm consists of tuo paaks 163 cm (strony)
— 1 —1and 109 cm (u>sak) both hat/ing ch..'-acter C . Ths peak at 19B cm is
•f A. character.
It is helpful tu carry out a group theoretical analysis of q = 0
modos. Treating the ammonium ions and uiatur noiaculas to ba rigid
clusters and using the external mode formalism the classif cation of
the q = 0 mo-Jus is found to be as follows:
For the K salt: 3A +3A +4BL +4B, +8E +2A +5A +48, +B_1y 2g 1g 2g y 1u 2u 1u 2u
+12E , and for the fJHA s a l t : 4A, +4A^ +4B, +4 B +1Ot +2A.u' 4 .1g 2g Ig 2g q 1u
+5A +5B. +2B. +14L .2u 1u 2u u
It is clear that the libracional degrees of freedom of NH, incorporate
12 additional modes of A *A +2E +B +B +2C symmetry spacieB, of
uihich A and t. are Raman active. Thus the abuvu assignment of the
three IT,odes as torsional modes is consistent with the group thecrutical
analysis. Further, a priori, it is not possible to Bay that librations
and translations do not mix, sine* symmetry considerations do permit
admixture. Hutuuver, if we follow the chanyus in Lne two p*aks (at
-84-
103 cm" and 196 cm" ) ae x is changed, it can throw light on the
possible character of the eigsn actors. In particular a sy&tamatic
decrease in the intensity of the peaks as x decreases from 1 to 0
would imply that these peaks must be largely libratiori^l in nature.
An at'ampt to ascertain this expectation is displayed in Fig.4.2,
where the observed changes in intensity of the two peaks uith x are
depicted The peak positions showed no changes, which conforms with
the expectation that the potential seen by NH. is unliKtjly to change
appreciably^ however the intensity doea decrease systematically within
the experimental uncertainty. It is, therefore, legitimate to ascribe
these peaks to the librations of NH*.
The external modes predicted by gr.-'jp theoretical analysis, above,
have been observed and some of them show an interesting variation In
frequency as a function of x. Uur results indicate that all the «od«s
show ana mods behaviour. The characters of modes more or laaa ramain
unchanged. Detailed analysis is being pursued.
Our thanks are due to the staff of the spectroscopy division for
allowing u3 tha use of their Raman Spectrometer.
1. Sea, for example, S. Nakashina, H. Mlshima'and H. Tai3. Phys. Chsis. Solido 35.8 531 (1974) and references therein.
2. O.W. Mellor, A Comprehensive Treatise on Inorganic and Theore-tical Chemistry (Longmans Green, 1946) Vol.3 p.188.
3. C. Vsnkataraaan and V.C. Sahni, Hsv. Rod. Phya. 4_2, 409 (1970).
(a) C«li viewed between crossed ^ 'jlarisers
(b) Cell \icwi-d between aligned polarisers
pig. 5.1 Phoioguiphs showing homeotroptc alignment of the liquid crystal, MBBA, obtainedv.ictjuni deposiu'd films ofCr.
-85-
5. HumuoL'rufous and Homeotropic Oriantatlun of Mematlca on
Thin F^lma. (K. Usha Ouniz, T.K. Bhaitacharya" and C. fianohar*)
Liquid Crystal (LC) optical displays haws become very Important
in industry due to their low power consumption and low cost* Display*
of two types are possible, onq using dynamic scattering properties of
LCs, and another using field offocts. Uf these, the field efiect
display .-.onsurnss less power but it requires good uniform alignment of
the liquid crystal molecules, either parallel (homogeneous) or perpen-
dicular (horaeotroplc) to the surface* of glass substrates between
which the LC is held.
Onu uty of obtaining LC orientation ie by vacuum evaporating films
of certain materials on the) glass substrates. Janniny haa recently
Q
indicated (.hot oblique deposition of thin films (upto 100A in thickness)
of Cr, Pt, Al, Au and Siu yiv/es a homaysnaous alignment while a film of
Cu yiues a homeotropic alignment of the L.C held between the substrates.
UB al9o have tried out an oblique deposition of Au, SiO and Cr on glass
plates in order to study tha type of LC orientation resulting from the
evaporated films. Uhile Janning-5 results tiers repeated for Au and S10
(a homogensous alignmant was obtained) a homeotropic alignment of ttvs
LC resulted uhen Cr films mere deposited I >iy.S.I shows photographs
taken of an LC cell in which Cr coated glass uubst.ratue were usod. The
homeotropic alignment of the molecules where the Cr coated cross of ths
top and bottom substrata overlap, is indicated by ths rscion in black
ir. Fig.5.1 a and ths bright region in Fig.5.1b. Ws hav» observsd timt
the henaotrcpic alignmant obtained is independent; of ths angle of
deposition of the Cr (ths,angle was i/aried from f3* to about 75*). Tha
orientstion waa also independent of tha thickn«na or the fllsj (SOA to
1000*).
-86-
workers >J believe that thci homogeneous alignment obtained
is due to the evaporated coating beinj deposited with a sawtooth sur-
face prafilu whoou snaps* deptmds on the oblique angle of incidence.
This is true of Au and bid films, where homogeneous aliynmant is obtai-
ned only s/hun tne deposition is done for certain rango of angles of
incidence. The homeotropic alignment of the LC in the case of Cr
films cannot be due to a sawtooth surface profile since this orienta-
tion is independent uf the angle of incidence of the Cr deposited. One,
therefore thinks that one of the following two reasons might be lead-
ing to the LC alignment in this case.
(1) Flicrocrystali of Cr (or its oxide) might be growing in such a way
that tha molecules of thu LC are held in a homeotropic orienta-
tion due either to interactions, or to geometric considerations.
Ue feel this might not oe a valid reason since the electron micro-
photographs of 30mb of the thin (50°A) Cr films we have deposited,
show that parts of the film have an amorphous structure.
(2) It is possible that if a magnetic oxide of Cr is formed (eg.CrO)
on the substrate, local magnetic fields present, might cause homeo-
tropic alignment of the LCs.
There could also be other reasons for the alignment caused by Cr
deposition. Ue are at present trying to find out whether one of the
above two reasons are valid, by studying electron microphotographa and
Raman scattering from films of Cr. It should be noted that the LC used
in all our experiments was I1B3A.
We have made successful electro-optic field effect displays, using
Cr coatad conducting glasses. The LC used in these displays was also
I1BSA.
-87-
* "Laser Section, BARC.
•Chemistry Division, BAHC.
1. J.L. Janning, Appl. Phys. Lstt, 21., 173 (1972).
2. U. Urbach, PI. Boix and t. Guyon, Appl. Phya. Latt. 2J, 479 (1974).
3. U.D. Dixon, T.P. Bcody and W.A. Hester, Appl. Phys. Lett. 24,47 (1974).
6. Comoton Scattering oft-rays from Polycrystalline Tltanlurc
(P. Chaddah, U.C. iahni, K.K. Rao and N-S. Satya Plurthy)
Compton scattering studies using both X-raya andY»rays provide
a raaens to probu the momentum densities of electrons in solids. This
opens up ths possibility of subjecting band structure calculations to
exhaustive teats. The use of "-ray sources, father than X-ray sources,
offers the advantage of higher counting rates, purar incident btam
and simplar data analysis, and facilitates the study of high i materi-
als, experiments in this area havg, thereforu, been initiated in
our laboratory. Since a 5i(Li; detection syatsm and associated alec*
tronica was readily available luith the fission Physic* group, w«
attempted a preliminary study of y'-ray compton scattarlng fro* titanium
in order to explore the feasibility of usiny that syatem.
A schematic diagram of the expeciaontal setup is shown in rig.n.1.
241 ' *•
The source used inaa Am (59.54 keV i-rays), and ths detector-cum-
analysor system comprised of a Si(Li) detector, a noise preamplifier,
an amplifier and a 512 PICA. As the sources available war* quite
ue used six sources simultaneously, which added up to give a 'source
strength*«15 mCi. The scattering angla was fixed at 155*44*.
300
3.8 mm. THICK Tl
400 450
•CHANNEL NUMBER
A scnsnutie cUagr.-o ^-r t.na
-"4m scufcs* <<ecd OJJCJCin t?:a caiiiiaxirg !i.s«*
th-j jyt^cior ".i-roug."1 lilt
ons of th* ** louroa (intuBa nunicer 1^ i» i^a+n in
The Conpton Prgfiia of poly-cryitaUina titanium. 1smooth curve i i drawn t,hrn«9,itha uxparirasntal points is aguide to tha <ya.
-89-
Ccunts ware accumulated foe 13 hours, with about 400 counts/
channel at the peak. The compton profile obtainoo .(t> ..noun In Fig.S.2-
It8 full-width at half-maximum i» 1.8 keVf the detector resolution wa»
(F.y.H.n.) 530 eV (at 59.54 ksV). This broadening of tho compton line
agrees well with earlier X-ray results and y'-ray measurements using
• Ge(Li) detection system. Wt> thus find that- a Si(Ll) detection eystem
Is a viable alternative, and plan to use it in our future experiments.
uls are grateful to Or. b.S. KapoDr, S.K. Kataria and nadan Lai
Toe making available the detection system and eiectronice, and for
their helpful
1. P. tloenbergar and ».A. Raad Phys, Hev. ft^, 2C85 (1372j.
2. R.J. Weiss PhwB. Huw. Letters 24 , 683 (1970).
3. K.T. Bergyren, 3. Manninen a^d T. Paakari Phya. Rev. BB,, 2$1 ''1973),
-90-
7. Stark, Ladders in Sol^s (K.U. Bhaywat)
In continuation of the work reported / the problem of
finding the allowed energy levels af an electron in the superposition
of a periodic potential and a uniform electric field was studied. It
is now well recognised that one should consider only a finite crystal
and th« electric field should also extend only ouar a finite region
of space. Accordingly we considered a finita lint,as chain of S -poten-
tials with a uniform electric field superposed on it, Tha Schrociinuer
equation was solved In two different ways. Firstly we employed an
LCAU method and took into account overlap between all stnn*. This
•Java a good approximation to the solution. Next we obtained en exact
solution in terms of Airy functions. Both the solutions led to I tie
name conclusion, namely, that a weakly perturbed quasiledder can exist
under appropriate condition*. These conclusions are in ayreement with
those of Heinrich and Jones who also employed the LCAO method but
a parametrized form of the potential and included only nearest
neighbour interaction.
1. 8AHC 766, Nufiloar Physics Olvleion Annual Report (1974) p. 135
2. Hainrlch, J. and donea, H.Q. J. Phys. £5.2149, (1972).
0• On an llQaarlaatric In^nualltw for tneroy Leuele (H• Subtamar>ion)
[hers exists in .literature en interesting isoperimetric In-
•quality connected with the gcound state energy fur c« class of one-
-91-
potantials: of all the attractive potentials having a
given finite 'area' I V(x)dx, the delta-function potential h»s the
t Hlgenwalue. This inequality theraby leads to one of tha vary
few wnuwn lower bounds to the ground state eigenvalue, in contrast
to the variatiunal principle which gives an upper bound* The question
naturally arises whether it is possible to dsuisa an approximation
echaniB besed on this inequality for determining the energy levels for
• given potential. One such possible scheme would be to replace tha
given potential by a superposition of a number of delta-potentials
of suitable strengths Situated at appropriate points - the strengths
and locations to be decided on the ba»ia of some well-defined rules.
Thsrij on increasing the number of O - potentials one could hope to
get a better approximation to the eigenvalues. One such scheme had
earlier been proposed by ua and was found to lead to quite satisfactory
results not only for tha ground state energy, but simultaneously also
for the excited states. (ThB tutount of numerical calculations
involved in this *'hems is considerably less than In an analogous
calculation bane on the variational principles). It should be mentlnmd
here, however, that the convergence is poorer for higher excited stats*.
The main drawback of tha scheme was that it wss somewhat empirical, in
the naniif that rigorous proofs could not be given for some of tha
results obtained on the basis of numerical calculations made for sons
particular potentials* Ths task of supplying the nacnasary proofs has
bsan taksn up, and soms progress has already txen made. Tor example, it
has bBen shown that when one goss from n Q - potentials to (n+1 ) S
potentials (under certain conditions) ths groumJ state energy is pushed
up. We thus havB a sharper laoperimetric inequality than the one
-92-
aarliar and this is a crucial etap in proving tha convergence of the
approximation scheme•
9. pp ap flnomiMqMa Property at thB Plrec Haptmonlen With v
Uqlta-Potentlal ("• Subramania» and K.I/. Bhagwat)
In one of our earlier Investigations we had encountered a
curious phonomenont the (V -limit of the Qirac aquation Tor a particle
in a square-well potential (or any other suitable potential with a
O - function limit) is not Identical to tha Dirac equation with a
O - potential dirsctly incorporated in it. Piora precisely, the
•oluhiona of tha Dirac equation with a square-well potential does not
approach the solution of tha equation with & o - potential, when ths
O - limit of the square-well potential ia taken. This is in contrast
to the case with the Schrodingor aquation where au^h an anomaly doas
not arise. Carl^er we had simply drawn attention to the phenomenon
without giving a careful mathematical analysis to Identify tha source
of such a curious behaviour.
Hocantly Klauder has given another example of a similar nature,
showing that llm (H + All) / H for sufficiently singular V* It wasXHh° 2 3
followed by a careful analysis by Simon (and also Oa facio at al }
dealing with the cause of such a behaviour. We are now engaged in
giving a similar analysis to sxplain our esrlier results and to decide
which of tha two approaches is tha 'correct' ana. (This work wsa4
motivated by a comment aads by lahmann , who, referring to our boundary
-93-
conttitlons, states that only the § - iimU of th.
equation should bo considered as the correct one and not th. equation
with the & - function potential directly included. It is our
belief that th»r9 is no convincing reason to prefer on. ess* to the
othar and that 4ha anomaly i9 something us cannot remove This
work ia in prograas.
1. 3.H. Klaudsr, «cta Phy». Austr. Suppl. XI, 341 (1973)
2. B. Simon, J. Funct. flnal. Ijj., 295 (1973)
3. B. 0» recio and C L . Hammer, Journ. Math. Phys. 15. (7), 1071 (1974).
4. C. lehmann, Annalan der Phyaik 3£, 155 (1973).
1". On the Correctness of Slater's flotation. (I.V.V. flaghavacharyulu)
I. Introduction
Slater dsvelopad independently a representation theory of space
groups employing techniques and specifically notation different from
those of Seitz and WignBr. The notation employed by 31atar was cri-
ticised by Alttnan and Bradley on the ground that it does not properly
take into consideration the transformation properties of functions
cfefinsd on the configuration space.
In this work it is established that by taking into consideration
differant ways of introducing notation for defining mappings on suitable
sets of either spaces or functions over spaces or for the operations of
the symmetry groups, or the induced operations for the represBntatlws
operators or their combinations, there exist 32 different possible ways
of introducing notations in the study of symmetry of physical systems.
All these notations sre consistent henc'u Slater's too.
-94-
Curiously enough we hawe the surprising result that the Wignur's
notation though consistent in itself, differs from the usual notation
employed in roathGinatJral literature.
II. Theory
It ifa a well known fact that map^in.jS (functions) of onu set into
anothdc can be designated in two distinct ways namely: f: S-tS* can te
represented wh«n operating on elements of S either by f (e) = s' or (s)p
f s 61, uhaiti L and rt havu the obvious meaning. Now, tha notation for
2+2product of two mappings can obviously be chosen in 2 ways. Generally.
n-t-2if ue have n-mappings to be compounded W«J have 2 rules. Further,
there exists a dual relation among thesn notations which is obtained by
studying thasa rules from left to right or vice versa.
further, when ua deal with thb elements of a group G we can
naturally choose two ways of defining thu binary operation between
its elements of tha set with oc without an algebraic structure intro-
duced on tha set say for example G. or G . Now, on a set X, one can
R Lhave both the right and the left transformation groups H and 6
acting on It simultaneously, when ue have to consider the triple
product H © X @ G , Note that for consistency, we should have (H (SJ X)
t R L$ G •=. H ® ( X # U ) . Similarly, if a function is given, say, fj X-fr V
and the tronsformation group Gl,r on X, then we can introduce the
induced transfurination groups, acting on Y through the relation Y G •
(fftx)^Ldef A x G L ) = X ( f R * L ) L where Y « fRX, Note that ~ and %
arc introduced on ths group elements as they are used in a new situatioi.
Nuw, wo iu«i«t«c lie a feu important notations that are in use, in
literature.
-95-
H HUi.i)nt?r's Notation: Ufiyn(jr ur'Ha f ,G. acting nn thu (column vector)
space X leading to (tho column vector spaca) V and X, rsspsctIvdy with
R Htha induced tranuf otraat io" on f bainy given by k •
H HSlatur'a Notatlont 51attr uses f ,G, acting on the ^column vector)
space X leading to (the column vector spaces) V and X respectively,
K Kwith thu inducud transformation on f given by ^ •
Natural Notatlont On this one uaaa f ,G acting on the (row vector)
apace X leading to the (row wactor) spaces Y and X respectively, with
the induced transformations on f given by G. .
1. O.C. 5later, Rev. Plod. Phya. 37, 68 (1965)
2. 5.L. Aitman and C.J. bradley Rev. liod. Phys. 12^, 45 (1965).
11. Scattering Tengsra for Hesonanse Hainan Scattering in ClosB-Packeg'
Hexaoonal Lattice. (I.W.U. Haghai/acharyulu )
I. Introduction
1 2
It is established by 81rman and Beronson and dirman that tha
Inelastic Raman Scattering tensors of light by phonons or othar excita-
tions in crystals can be discussed in an alegent way using linear com-
binations of Cl8bBch Gordon coefficients. They have established that
the first order scattering tensors are certain linear combinations of
Clebsch-Gordon coefficients; and the second order scattering tensors ara
bilinear combinations of Clebsch-Godon uoafficients and so on. They have
illustrated their results for thB C B S B of CII^U crystal.
Tha aim of the present work is to discuBS the first and second order
resonance Raman phonon scattering tensors in class packed hexagonal
lattice structures. The theory is generalized into the general frai,ia work
-96 -
uf induced lupiotBntaiiun thuor/ Hnd ifa s impl i f ied. buitoble alijoiithetna
UDL.iiniMQ similar results for uthur spaca yroupa aru discussed.
i.^l'.r, *H(? notdLian of Uirir.an l i . t Vi nh^i the scattering tensor luhich
i!; uauaily u function of1 k , k. ant) •( uh«rti k and k era respectively
-»
Incoiiny and uutgoiny prapayation uactors and 't is tha position vector
—* --yo( thu scat Luring ions. Suppressing k. and k- dependence, ua expand
whera tj; = (J)( J^, ... Jn) ond (o-) - (rr , •••^) and
( j j Jj,W -• // U is the factor (jraduciny n-phonon acattacing.
(••-) j T-,-
T ! I B t i r.'-.f o r m a t i o n uf P. . ^R ) unoor a spa^u yroup o p e r a t i o n bshaues
r ' -. • i i l.n t.ne ri-th order procesB
» • ' i f i ) "s=~ P IR ) JK y" / _ S S D (* S ) P
...bore O l u ' ; (3) = DVJ;(S) D (S)__ . . . . 3 ,'S)
th«n proceeding as was done by Birman us obtain
whore K(o-'} dapenda on the indices of thu irreducible representation.
Hou 0* ^ '(S) corresponds to the symmetrized mult iple product of tha
irreduclt j lu reprusentstion 0 . The aquation (1) indicates that the
crystal scattering tunsors ere obtained as the nth order l inear combina-
tions of the I. lBb sen-Gordon coeff ic ients. The vanishing or otherwise
uf an bleuibnt of ttie polar izabHity tensor is very much dependent on the
-97-
lepresuntation D of ths spac3 group under consideration. In gunerel
thasg waniBhing elemants are not the tsams for all the spaca of groups
thot have the same underlying symmorphic space group structjre.
Nuw maxing use of the results of the author ' in the reduction of
0 (R) the evaluation of P \ [ can ba carriud out efficiently for the
differant space groups under consideration. Specific details in tha case
of th«> clouepackud hexagonal structure are ohtained.
1. O.L. Birman and R. Barenson Phys. Hew. £9_, 4512 (1974),
2. J.L. Birman PhyB. Hew. U£, 4S18 (1974).
3. I.U.U. fiaghavecharyulu (see the foliouiny article
12. Sy.timiitrj.zed Plultioie Products of Induced Monomial fieprssentation
(I.V.U. R8ghau«charyulu)
The well known results of symmetric and antisymmutric squ«r«s of
induced representations nave bttan generalised to arbitrary symmetrized
multiple products of induced representations. The study of these pro-
ducts 19 important araony other things to obtain the selection rules
for different physical processes taking place in crystals. For instance,
Bee tha abous article for obtaining the nonuanishing polarizabiiity
tensor elements.
These generalisations are obtained by considerably sintplyfying the
induced representation theory of finite groups. Induced monomial raprs-
sentatiens over suitable subgroups are used in the above generalisation
procafes. Henca no uhtre the results from the theory of finite groups
such as decomposition of representation into irreducible representations
or the orthogonal or completeness relations are used. Further, the basic
-98-
theorems of the theory are obtained as consequences of a naat book keeping
of the factors of group elements when thay are written in terms of the
fc& of s subgroup and ita cusat representative elements in the groups.
In the first part of this work the basic concepts of the theory of
inductij iypresontations hauu bean established. In the second part>the3e
results have been extended to normal groups. In the third they have been
uxtunded to tansor products of groups both external and internal. As
natural consaqutince of this theory we obtain the reduction of the symme-
trized multiple prouuets of the induced representations of groups.
- 9 9 -
I I I . WUSSBAUCK 5PCCTRA AHu HYPEHflNL flELUS
1, j*lictoniaqnetic tlehaviour i n Co-Ga Alloys. {,H.H .P.n. Rao
and P.K. Jyencjar)
Invuat icj^tian uf tim local atomic unvironmont effuct on thu
maynetie properties of thu intermetal l ic alloys Co-Ga uus carried
uut in view of tha intsrest lng preliminary results obtained ear l ie r .
In tha present study fiossbauar maasuremunts on the alloy Co _J . jut)
Ca ,,-{ fe), effect of thurmal treatment an the magnetic properties,
NflR study and correlation uf the latest existing susceptibility and
2magnetization date of Co-Ga alloys tn relation to the magnetic
properties observed in the flossb^uar measurements on thBSe alloys were
carried out* The earlier measurements showed the ptesenca of both
magnetic and nonmagnetic phasus depending upon thair local atomic
environment but their relative proportions could not be understood
quantitatively. Tha present study of the ef-foct of heat treatment ha6
shown that there is atomic clustering in the slow cooled' samples. This
atomic clustering was seen to yive rise to short range magnetic ordor-
ing in the alloys. Thus in slow cooled samples, the relative proportion
of the magnetic phate was found to be larger than could be expected on a
eimplB binomial distribution of the atoms and this clarified our puzzling
results obtained earlier. The presence of both the magnetic and non-
magnetic phases, the distribution of the magnetic hyperfine fields obser-
ved at the re impurities occupying the Ga sites, the nonlinear Arrott
2. 2
plots (i.a.,cr~ Vs H/if) observed by Amamou et el and the considerations
of the psrculation limits for the manifestation of long range magnetic
order, indicate ths presence of short range order in these alloys and
further that the system belongs to a new class at magnetic systems which4
exhibit "mictomagnotism". NP1R measurements on Co Ga has shown that
-100-
thsre are nonmaynetii; Co atoms preaent at thu regular Co sites and
this tesult supports tha Mossbauer results cbtained.
1. K.fi.P.II. Hao and P.K. Iyengar, BARC-694, Annual Report of theNuclear Physics Division (1973) p.129.
2. rt. Arnamou and F. Cautier, J. ^hys. F. Pietal Phys. 4_, 563 (1974).
3. K.3. Juff and U. Cannella, Proc. "8thand Maynfetic Waturiais, Denvur, 1J0, 54
4. H.A. beck, ilet. Trans. Z_, 2015 (1971).
3. K.3. Juff and U. Cannella, Proc. "8th AI^ Conf. on Magnstiewand Maynfetic Waturiais, Denvur, 1J0, 541 (1973).
;.. Soin Relaxation Lffects in Wickai-Zinc Ferrltgs uslnu tha
pjpfasbauer Effect. (S.C. Uhargava and P.K. 1/engar)
A number of studies have been made on nickul-zinc ferritoo
oarlior. They, however, did riot cowor the concentration range or
the temperature ranyn sufficiently, to reveal correctly the affects
of spin fluctuation.
In the present work Mossbauer spectra of thrae compositions of
Hi In. ro2Ua ^x = <J'2^' °*5 4 0.7b; have been recorded at several
temperatures below their ma90stic transition temperatures. These
spectra enabled us to establish the presence of ionic spin relaxation
effects and tha absence of supurparamagnutism. Another aim of the
study has been to deturmine the effect of replacing cobalt with nickel
in cobalt zinc ferrites on tha behaviour of relaxation time of Fe
ions uhich u/as determined in our earlier work.
for the computation of the theoretical spectra, the stochastic
model of ionic spin relaxation devulopsd by f. van der Uoudo and A.3.
Dekke?, and !"!• Blume has been used. The niathod of comparison has been
-101-
in detail e l&euihert . Only two identities namely, the
t 2h Ha\relaxation time and S = axp I r—=—I (where H is u/aie molecular
field) hauu bt;en trusted as uariabla parameters.
It is found that the broadening and modulation of line shape can b£
completely accounted for using this interpretation. Typical results of
such comparison have been shown in Tig.2.1. Tha dependences of the
n +n times un tht-> uuncentration of Zn + ion'i arid the temperature
aro Bimilar to tho buhawiuur found earliur in cobaJt zinc farritBS.
This substantiates our mtarpre'ation of the cauiio of tha high walujs of
lulaxation time yiv/cn earlidr, v/iz. that it is dut* to the loss of
v"•'W-'
~ w ^ x r v"• ••
W v"1/" V\
J
' 1 Tin t»i<«m?tluil a,'*>. u n wl.
• -u,. t."..r» - I 1 D'K t«in t:".v,
correiated motions of spins (due to ths transuersa coiRponent of the
exchange interaction) at neighbouring sites.
-102-
1. "Spin Rblaxation in Disordered Nickul-Zinc rerrites usingMossbauur Effect" by S.C. Bhargava and P.K. lyengar in Proc.of Int. Conf^ on thu Application of thu i-iossbauer tffect huldat Sundor (France), 1974.
3. Flossbauer Studies of fe pa-. (S.C. Bhargava and P.K. Iysngar )
Fe Ga alloy possess BQ.. Lyps crystal structure. Ptosabauer mta-
eurenients have been carried out at seuoral Luniptrciturss in the- magne-
tically ordered phase of the alloy. Thu Curie tbrnpurature has buen found
to be (A69+1 )°K. Using the least squares fitting procedure, thu spectra
have, buen unfolded into three component sptetra and the tomperaturt>
dependences of the hyperfine fields charaLttirisiny these spectra have
been detunuined (Fig.3.1;, In addition, thd relative areas of the com-
t u n IM spin t i ( /2r« also shown
Twnp«r«iurt d«ptnd«ncu or «i« m a y w l t tl«Mseharactfrislrtf. th* thrf« cpmpoMnt tpactra of
ponent spectra have been determined which are not consietsnt with the
earlier belief that 2(a) sites are completely occupied by iron atoms and
the remaining iron atoms partially fill 2{d) sites. The relative areaa
of the component spectra are temperature independent implyiny that the
three recoilless fractions are not appreciably different from each other.
-103-
T:it- velocity bhifts <?t dif forunt temperatures .':&r impending to the mott
intoriht1, i ( a ) s i te , component spectrum have bfjen f i t t«d with th£ oxpfo-
ssluri
F(T) = E"| + £T - 7.30bx10~4 " 0E J_y? + (explOd/Ti-1)"1 I
unlng the loast squares f i t t i n g procfidurt^which yavn the f o l l o w i n g
Isomm shif t (0°K) = U.64 ± ° ' u i "»/»BC
f = -(7.U>2.0; x lu"S ram/sue
A = (420 + 40}uKVe
Tht -we ualua of the temporature coefficient of the i»u"ier shift
i^ an intureating result and shows thu pret.int.fc mf tht» explicit taiiip-
s-rature dependence of tha i&omur shif t . Similar result uas found in
LoroGe earlla?. These results arise due to the larger occupancy uf the
orbitals of Pa.
1 . H.K. Perkins and V. Ha2ony, Phya. Hev. B5_, 7 (1 .972) .
4 . noautauut Studies of (Co Fe )_Ge . ( S . C . Dhargava and• • x i —x 3 o
iJ.K. lyongar)
The alloys (Co fu, )cGe, >«ith compositions x ~ 0.0, 0.15, O.-i,
U.45 and 0.7 have beun piupaced and studied usiny Moiisbauar spectro-
scopy to determine the effuct of replaciny iron with cobalt if» Fa5tH,,
which provides one extra d-ulectron for each atom substituted. A l l
the compositions possess the B82 typo crystal structure), iptctra
recorded at tJi.'°K have been ueed for Ihe purpose, and tho least-fctjijcu es
f i t t ing procedure has beun ui>ed to unfold th.j ccniplux shapes of
-104-
epectra into tna componunt spectra. Thu measurements showed that
whereas the internal field at the 2{a) site is independent of this
substitution, the field characterising the other tuo component npactra
Changes appreciably. Further, cobalt has been found to poaaase greater
preference for thu 2(a) site than the othur eltes. Our oarlier studies
hat/u shown that the behaviour of iron at 2(d) is sane both in CofeGt>
end CoFoSb. The results of these studios uhuu that the value of the
atomic moment on tho 2{d) site decreases in qoir.y from CufuGe and CafuSb
to fe G» «nd decrtsasBS further in going from F<vGe., to iCon .rFt,, ..^JGB,.
1. S.C. Bhargaua and P.K. lyangar, Prawana 2_, 126 (1964).
-105-
E. EXPERIHCNTAL TECHNIQUES AKO INSTHUHEaTATIOH
1. Isatopa Separator (V.A. Hattangadl, F*f*- Bhathsna, K.L. Petal
and E . ShalJLon)
The nachining of tha Main analyaing aegnet for tha aaaa separa-
tcr under construction, OUflAS la nearlng completion. About 18 out of
2 0 yoke Members hava bean fully machined end tha Machining of tha
remaining piecaa is in progreaa. The manufacture of tha enarglelng
colla for tha Magnet, which haa baan entruoted to a local engineering
firm, is in progress^ a amcllar trial pancaka la balng wound for initial
proof taata. A number of alacttical taata ware carried out on the
eavplee of epoxy pre-iapragnatad fibre glaaa tapaa balng apaelally
Manufactured for ua and initial difficulti.ee due to aolatura abaorptlon
in bxtfe'r-Q humid snvironment hauB been ouercome by applying a- thin
t'xt"r.i Ciist of epoxy botii before and after the taping process.
The assembly of the vaouua ayataa - coaiprielng of four large
vacuu* chambare for tl-ja ion source and collectore, with individual
pumping aoduloa - the powar auppliee and other aleotronlc inattuaanta
haw already been completed and teatod. Tha aaln rotary vaeuua puap,
of 5000 It/at, capacity waa procured and taatad aatlculouoly with con-
tinuous operation foe 8 to 10 houre dally for over one aanth prim to
lta acceptance. Tha puaplng epead aharaotarlatloa of tha puap Mra
aaaaused and Monitored eontinuouely during thaaa taata. A 4 a dlaaatar
vaouua lino haa been constructor for oannaetlng tha aain votary ptmp
to the varloua puaplng aodulae. A 10* erlflea# alUlnf gata valva haa
aleo bean fabrieatad and afo«ad leak tlght| thraa aara fata valvaa ara
at praeant under production>
A eaall portable, d.o. aapllfler circuit haa baan built far uaa
-106-
wlth tharaocoupla or loniaation vacuwa gauga far rough laak datae-
tlon. A high currant ehoka flltar olroult waa addad in aaoh mt tha
ion aourea powar auppiiaa. Tha control olrouit for tha ian baaa aoannar
waa laprovad by introducing auto raac-Uing of tha fllp-flopa far aaoh
eyela. Tha coannar haa baan taatad with an actual ion baa* froa aur
ion aaurca on tha taat banoh? ' Tha vacuua Monitor eircuita w » a alac
•odifiad for buttsr operation and racalibratad. All tha inatruaant
and othar panala on tha control daak hava baan givan tha final flnlah-
ing touch with painting, calibration ate*
Tha axparlaantal invaatigation of diffarant typaa of high currant
ion aourcaa continued throughout tha yaar. A now hollaw oathoda typa
ion aourca haa baan diialgnad and fabricatad* prallalnary taat ing of
tha aourca ia now 1P prograoa. With aro curranta of about 2A, axtractad
currant* of tho ordar of 140 1U hava baan achlawad fra* an aalaalon
orifiea of about 20 alia diaaatar which aaana an axtraetad Ion currant
danaity of 60 aA/oa • Furthar iaprovaaanta and atwdiaa ara undar oan-• • • . • . ' . ' • • •
aidaration. Tha Ouaplaaaatron Jon Sourca waa alao rahaahad and oparatad
to givo 4 aA OKtractad ion currant froa a 10x0.4 M 2 allt at 30 KV
axtraction potantlal aapwnting to an ion currant danalty af aaawt
100 aA/ca2. Howavar, It waa faund that tha allgnaant mt tha aalaalan
allt with tha aouraa axla balng vary crltieal raaulta ara nat vary re-
produeibla. In tha law voltaga ara. typa aourea, tha fllaaant aita waa
incraaaad froa 1 aa dio to 1.«3 aa dia tungatan wira ta lnoraaaa lta
lifa to about 12 haura undar larga mee eurrant eanditiona. Tha fllaaant
poata hava baanradaalgnad %o tafca tha largor filaaant aurranta, af tha
ordar of 1S0-2D0A, with watar aaalad auppart .alaaka. Tha flaating
alactroda, which uaad to gat daaagad fraquantly dua ta alactran aaabar*-
aant, haa baan raplaoad by a aaall tungatan wira( which alaa aarva* aa a
-107-
pvabm for ••••urlng Ion denelty behind tha aalaeion «lit. *
m»un«nlcal reaota oontrol ayate* for adjuetaent of dietence and
replantation or the extraction alaotroda with roepect to the ion
source eaieaion «llt baa baan oonatructad and mounted in one of tha
ion source llaba for tha »••• aaparator and It 1« baing taatad out
at preeent.
t- « Beam Profile "orator - Papar praaantad in Hue I. Phye.* Solid Stata Phya. S/ap., Boabay (Dec. 1974).
•This work waa dona in collaboration with Dt. P.K. 8h«tt»<3h*» y«of Ion Implantation Croup.
i . Van da Craaff Operation
Tha Machine oparatad norwally Mil thn and cf Xi£y 197*, whan
it waa closed down for aalntananca and for inatallatlon of Ma
inti source*
Tha Ha++ ion aourca waa lnatalled and Ha baaaa of /«/100 nh
•,J to obtainad. These wara taatad by Rutherford scattering and by a
of f -apectruM following tha Ca(«<,n) Sa reaction.
Our ing the la t ter half or tha year tha Machine haa not been
well Mainly dua to weeuue) probleaa.
Wuc^ar pa tac f ra Sactiaw {1.0* Oande,. IUC. Jain, A*S. Udyawar*
C.V. Shanoy, 5.R. Chinehanikar and * . P . Bagool)
fjeutran
Th« neutron radiography f a c i l i t y at Apaara waa uaad for tha
foilowing lnapcction world
i ) Two 4 .S a Marker Shelle of Nawal Araaaent Inapaetorate
ware radiographed i n the noee-cone eection. Air cavit iaa
in tite Phoaphorua charge aa well mm praawice of water wee
-108-
dstected.
li) Eight electric detonators of the Air Arajsasnt wing of
Directorate of Technical Production and Davalopmant (AIR/,
Iliniatry of Oafanca warn cadiograohad successfully. Thses
datonatora consist cf tiny aluMiniuM tubaa rillad with co«-
pacted baaa charge of Tetryl and primer charge containing Pb.
The X-radiography waa unabla to image the base charge. Tha
neutron radlographa wera able to enow both tha baae and
primer charges clnarly aa wall aa other co»ponenta like fuea
head, rubber plug and lead wires.
lii) The Metallurgy Division of 8ARC ia developing a Boron- .
Aluminium composite material for uaa in the neutron*baa« gataa '
for the R-5 reactor. Tha diatribution or boron in tha COM->
poaite ia of prims importance in the evaluation or the materiel
aa a neutron abeorber. * 10" x 6" x 0.5" eaapls plats of this
composite material waa radiographed in aactiona. Tha raault-
ing radiographs have clearly ahown ragiona of inhoaoganuitiea
in tha Boron distribution.
b. Nuclear Petectora
i) BF- and He-3 Oetactora
A total of 52 BF, and Ha-3 Proportional Counters have bean fabri-
cated and euppliad to varioua diviaiona of BARC, as wall as TlfR.
11) Poaition Senaitiva Detector
A Unaar poaition aenaitlva detector, for snail angle neutron
scattering experiments ia under devalopasnt. This usss • high rssls-
tancs anods wire in a conventional proportional detector. Tha charge
liberated by the incident rsdistion divides iteslf on ths snods and
glvss riss to two diffsrsnt pulsss P and P_ st ths two snds of tha
-109-
anoda. Tha ratio P../p1+p
2 *• * »•••«*• of tha position of inoidanca
along fcha counter axis.
« 30" long, 1" dia counter haa baan fabricatad with a graphitu
cuutetl gutiiti fiJdiiient, yivinrj about 2.5 kA./cm. The filament was fabri-
catad in the laboratory. Fillad with 2 atm. of Ha-3 gaa, tha datmetor
ahowa reasonable FUHPI raaolution for theraal neutrona. Preliminary
taata with tha counter ahowad that P., and P wary with poaition of
lncidai.ca. A pulse summation and ratio circuit ia baing developed with
tha halp of Electronic* Division, for vigoroua poaition taata.
ill) Soft X-ray Oatactora
A total of 22 detactora for floaebauar Spactroaatry hava baan
fabricatad and auppliad to varioua uaara, including HT'a and BOM*
univeraitiaa.
A torrodial X-ray datactor, for back-acattar Boaebauar apactro-
matty haa baan made. Tha aourca radiation paaaea through the datactor
on to tha aampla undar test and tha backacattarad radiation gat* datactad
in tha doughnut ahapad aansitlva volu«a. Tha detector faaturaa a
damountabla nylon conical window and a grid alactroda for corraction
of flald distribution* naar tha anoda laad. Fillad with Kr-CH.
•ixtura, the datactor haa a 3.5 kaV raaolution for tha 14.4 kaV
photona.
*. (a) Ion Iwplantation (*.C. Wagh, P.K. Bhattachaty* and N. Sarwa)
naaa analyaad haavy ion beama from tha Ion Iaplantation
•ant in the Van da Craaff Lab. hava baan utiliaad to atudy p-n
Junction* foraiad on ailicon aingla crystala and aaaaura tha changa
in indax of rafractlon of a thin iaplantad layar on glaaaaa. Cxparl*
Manta with warioua computer programajod haavy ion proflloa in thaaa
•ubatrataa ara in prograaa.
-11C-
A thtaa part analyeing aao.net haa baan installed on tha beam
line of tha Ion Implantation facility, Tha thsraa porte 'ar« at 11•,
36s and 90*. The aagnetic field ia produced by enargieing a coil
Mad* of 1.25 cm aquaca aluminium pipa. A oonatant ourtent pswer
•upply capabla of delivering upto 250 ampa into tha coil piawidaa a
•tability of better than 0.1 per cant in the aagnstic field at 6 k
gauaa. Heavy Ion* emerging fro* tha 400 keV Van da Graff accelerator
are focueaed by Means of an electromagnetic quadropoie lana eyetem,
•aaa analyaad with this magnet and awapt uniformly over a lerge rec-
tangular area using eleotroatatic beam dedectore. Baaa curranta of
0.1M,A/cn ciar a 3 CM equere at a diatance of about 5 aetrea from
tha ion aource have been ueed for iona produced from a aolid charge.
Singly charged gallium ion beama from thie facility w»re employed
for bombarding low reaiatiuity ( 1 to 10 oha-cm) n-typa ailicon cryatalBi
Tha cryatal aurfocea expoeed to the iona ware poliahed to *n optical
finiah end cleaned thoroughly with electronic grade cheaicale prior to »
i radiation. Tha ion fluencaa ranged between 3x10 and 3x10 /am at
warioua enargiee between 100 and 200 kaV. The cryatal aurfacaa ware
approximately normal to^iiOtxii and no special attsapta uara aada to
avoid channelling of the beam. The implants ' region, a circle 2.5 cm in
diamatar, gave a allky appaaranca a*id exhibited Moh raalativity dua
to tha foraation of mn aaorphoua
Tha bombarded wafara wara annaalad in dry Nitrogan ataoaphara.
After a certain annealing atage (typically 3S0*C), tha iaplantad layarl
ahowed p-typa behaviour. Tha annealing temperaturea ranged batwaan
300 to 650°C. Tha anneal treatments were carried out in a ailica
auffla furnace built by our group. Surface raaiatlvity aaaauraaabta
on tha mnnmBlmd layera wera aada with a four paint probe. Tha ra>ult»
-111-
of a typical raaiatlvity va anneal temperature aaasurMisnfc for lao-
ehrenal annealing of tan ainutta ara shown in lTlg«l4«1>
RT Go* IM°LANT
n5
2 7«10"rf*0-3«'0"/cm Iat 200 K*V
• 10 mm.
JOO *00 SOO 600 1 »ANNEAL TEMP(°C>
Fly.4.1
natal contacts to a aaMiconduotor Junction play a vi tal tcl« in
lta oharactariatiaa. for tha f^matian at an ohalc contact to tha
p-typa layer, B O ^ auapotation, gold titaniua coMbination arid aluainlu*
"alloying" hawa baan axanlnad, Tha aluainiu* contact, in apita or i ta
poor scratch raaiatanea, haa proved to bo tha «oat satiafactory of
thaaa; poor adhaaion to tha ta«iconducto? aurfaea typlfiaa n gold av»~
poratad contact whila difficultiaa anccuntacad in pravantint) gold fson
diffusing into tha dopad layar waigh haavily againat tha gold tltaniuM
coMbination* Tha contacts wars Mada in a clacn awaporatbr i t 1Q**S torr.
Prior to avaporation, tha aaaplaa wara carsfully attlppsd Of mny oont«»
«inat£on and of oxlda prasant on tha aurfaca. During aluainiu« •vapors™
tion, tha crystal ta*paratvra> twa aaintainad at 200*C. Tha svaporatlon
was roliowad by • hsat traatasnt of tha wafar at 4S0*C for \i •inutss.
Aluaihius) is known to achiava a good dagraa of unlfora pon«tr«tion2'lnto
silicon undsr thsss conditions. For tha back contact, alsatrolasa
pickal plating waa aada on a lappad surfsoa. Phosphorous iintroducsd into
-112-
tns plated nickel by sodiu« hypbphosphite, ona of the ingredients of fchs
plating solution, diffuses into tha baae aaterial to soae axtant during
Bubesqusnt anneal traatment and ansuras an ohnic contact even for
thia resistivity ramje. Thean Junctions were evaluated after foralng
a few hundrad <ne«« structure diodes each a Millimetre square on a
single uafar. this was achieved by etching two seta of parallel lines
perpendicular i.i> aach other in succession on tha front surface ueing
wax aasking. I-V characteristics for the individusl diodes were sean
on a Tsktronix transistor curve tracer. A small variation in the
junction properties was observed for diodes on the sn«a wafer (Fig.4.2),
/i
i
...V 1ix
w
—/fT.
7 ....
rx:..--I :
WOUCi
I-....
....
•
: —1
1
.
—
1lilt-
fV iTir
.„! 1
„„
—
FORWAROi0 B V/dv —0 fnA'dv
"REVERSE:
1
• | - *PJU A/d».
Tig.4.7
On diodes showing the average behaviour, I-V aeaauraaants were Manually
made over a wide range of currants and voltages) the log I_ we V and
log IR vs wR data for a typical Junction are aaen in Fig.4.3. Ravaraa
recovery technique was af>pli»d to d»tar*ine alnority carrier lifetimes.
A forward bias is appllnd in order to inject Minority oarriars into tha
the lightly doped slue of the junction through a steady forward current
If. . The junction ia than switched to reverse conditions by aaana of s
sharp voltage pulse. This sweeps the stored charge rapidly across tha
Junction resulting in a raverss trsnsisnt current IR 'or a tlas t before
it decays to the eteady state value and the diode voltage enang.es its
-113-
Kf'
I R AMPS
Iff
10"'
RT 0 6 * SW K«V 3*ANNEAL •:O0*C 30
• 10- HT4
• FORWARD I-V
10
AMR
XT'
VR VM.TS
0.1 0.1 OJ 04 O.I
VF VOLT
O.«
polarity. The c^rriL-r lifetime T is computed from the relationship:
A study of the junction between the Implanted layer and the under-
lying aubstrnttt orfgrs a direct uay of estimating thB semiconductot
device and yields valuable information ..bout minority carriers and recom-
bination-generation centras. H<JUIRWI.T, UUch work is scarcely reported in 1 Ua-
rature in comparison with the investigations on the conduction phenomena in
thp implanted layer1, whit n are noucrneci1 by the majority'carrier behaviour.
Th» for-.rd i-u eurvm of thtaa Junction, folio*, an Mponanticl
-114-
relationehip. The exponential factors U s between 1.5 and 1.8 indi-
cating a dominant raeonbination currant component. The revereo oha-
rectaristica wary cloealy obay I^(WR+V )" but display rathar aoft
braakdowna indicating that tha damage axtanda bel»w tha iaplantation.
Minority carrier lifetimes hava baen obaarvad to b» around 1 micro-
second, leading to an eeti*ate otf\Q /c.c. for tha dafact concen-
tratlan below the junction. Tha junctiona foriaad in thia laboratory
axhibit highar raveraa breakdown voltagaa and oarrlar lifetlmea in
oooparison with Ga* implanted diodaa reportad eleewherel '
Tha dopant concentration and profile can be indapandantly and
accurately controilad by tha tachnique of ion implantation. Tha f«aai-
billty of exploiting thia fact to produca implanted raglona of hioh
refractiva index to pradatarminad thicknaaa on glaaaaa haa baan
invaatlgatad. A light ray launched in thia ragion can cowar long path*
with llttla loaa in intanalty by rapaatad total internal reflectiona,
prowidsd tha rafractive index of thia layer axceada that of tha aub-
atrata by 0.01 or nora. Such a ayatem finde ready application in thin
optical wave guidaa uaad in optical comaiunlcation ayate*e; '
Strainfraa, optically flat and clean aaajplaa of boroailicata and
pyrex glaaa ware iaplantad with 75 to 100 keV Ga and Ar+ baaaa, tha
doeaa varying froaj 10 to 10 iona/ca . Tha refractive index of tha
dopad layer wee then naasurad by tha Breweter angle technique. Ueing
an optical epactrometer in conjunction with e photomultiplier tube,
reflectivity va angle of incidence •aaeuraaanta ware aada on tha aaaple,
bafora and after tha irradiation, whan illu*lnatad by light polariaad
in tha plana of incidence at S893A*. Tha angle at which tha two reflec-
tivitlea bacoaa equal la tha Braweter angle for tha laplantad lay«r,
aaauailng no loaeee.
-115-
Tha rafractiva indax of tha bombardad lay at la sbawrwaaV to,.
vary linearly with doping cone. Nd in tha foras n • o +(0,6x10 to
10* )Nd. No aaturation in rafractiva indax aeama to h«v« teaan
attained avan at n • 1.8 (Flg.4.4). Tha aachanla*. Mainly raaponaibl«
for tha change in indax of refraction appaara to ba the diaordar
produead by tha lncidant anatgatic iona Knd ia in agraa«an£ with tha
thaory•(5)
• 0 »•* 10*"' 1*10" UK*
lOMC COMCENrFAHON Ol f 1t o " nv"
lONK CONCENTRATCN cnf»
Fig.* . *
1 . P.K. Bhattachacya at a l . , Nucl. Phya. * Solid Stata Phye.(India) ISa. 254 (1973).
2. H. Saiio, Oh*ic Contacts to So«lconductocs (adi B. Schwartz,ClactrochM. Soc. Inc., 1969) p.277.
3. 3. Staphan tt a l . . Radiation Crfacta £, 73 (1971).
4. 3.C. GoaU at a l . , *ppl» Phya. Latt. 2J^ 72 (1972).
5. C.R. Schlnaller at a l . , a. Opt. Soc. taarica, J^, 1171 (1961).
-116-
4. <b) Instrument Development (P.K. Bhettacharya, fi.S. Bhatia, A.
and N. S«rmc)
Oaalgn construction and aaaanbly or tha ton injactor for I.C.T. -
ion implanter ha* been compla&ad. Various Ion aourca geometries for a
high currant density hollow cathode Ion source (designed and teatad in
collaboration with Shri tf.A. Hattangadi) hawa baan triad and typical
axtractsd bean current of 12OyUA of Ar+ waa obtained with emission2
current density or 60 mA/cm . An einzel lans cum extractor, conaiatlng
oT a gap lens and an einzal lena waa deaignad and tha geometry waa opti-
mised for 15" bean divergence of heavy ions from tha preaant ion source.
A 15° Magnet waa asserted with required field coils on the pole piaea
and yoke waa redesigned with a suitable magnat chamber coet, effort and
time. The beam of positive lone upto mai?s 70 would bo bant, analyzed
and dispersed into the accelerating tube ot the I.C.T. - ion
implanter. Supporting instrumentation ia ready to be put on teat.
5. An Insulated Cora Transformer Pouier Supply for Ion Implantation
(I1.S. Shatia, N. Sarma and C. Paramasivan)
I. Introduction
As part of a new low cost ion implantation facility a heavy ion
accelerator of 200 kilovolt energy and beam current of upto ten milli-
smperes ie under construction. The power supply, used in this machine
is described in this report.
Comparison of the various possible alternatives for the genera-
tion of the high accelerating voltage ahowad that tha insulated core
transformer was the most economical and one for which components would
be readily available. Direct rectification of high voltage alternating*
current involves an expensive transformer with high voltage rectifiera
and capacitors which are difficult to procure. In a cascade or voltage
-117-
muitiplylng circuit again, capacitor working woitagei ara hiBh and ••
• reeult fchaaa capacitor* haws to bo made or i.postsd. *.*• ripp*» lf>
both thaae circulta tend to be higher th.n in tha inaulated cora trana-
fortnar (ICT>. Charga transfer »achine» «uch aa the Van da teaafr cannot
dallvar larga outranta without a B'aa^ deal of dawelopnant affort.
II. QaacriPtion
Th» ICT ecwpriaat a primary »ectiOn (Fifl.5.1 ) or. which «r« atackad
t . n aacondary aactiona. The input po-er is euppliad to tha pri«ary fro»
• 440 volt thraa phaas aupply connected throu9h a thraa phaae w«ri«c
( F i 9 . S . 2 ) . Tha three primary coils conBiot of 800 turna aach and «ra
connactad in da l ta . Each secondary aectlon has on Bach phase a 6600
turn windino which provide* ^300 vo l t t A.C. Each of tha.e -indlnga
givea Input to a f u l l wave woltag* doubier c i rcu i t with 0.02 nicrofarad
y KW cepaoitora. Tha three rosultino 6.6 KU DC woltage* are eonnactad
JOOjl —
NVLON SUPTODT BOO
fflg.fi.1
—718-
BASIC HIGH VOLTAGE UNIT
PHASE 1
I l i j . 5 . 2 ELECTRICAL WIRlNO DIAGRAM OF INSULATED CORE TRANSFORMER
in series, thus giving 20 KU D«C. par secondary section. The iron
core or each phase wiping is inauiatad for 20 KW from the next lower
core section by fly la r. A trickle current is drawn by a resistor
chain and the voltage measurement is made on this load. In addition
three phase power of upto 3.6 KUA is provided through the same core
at the high voltage terminal from six coils, each of maximum voltage
230 volts and 3 amperes.
The choice of placing the accelerating tuba outside the power
supply led to a great reduction in size. In our design calculations
e flux density of 1 webar per metre and a voltage rating of O.S volte
per turn was assumed. The voltage in each secondary coil waa kept to
3300 volts and the maximum currant to 10 milliamparea. Within these
constraints, all other dimensions and parameters were optimieed by a
computer programme for minimum cost and size, consistent with the
performance ratings for the components. The final deaign is shown in
fit}.5.3. The entire supply is JO cm in diameter and the height of
93 cm was maintained since the supply is meant for open air operation.
To obtain an accurate coet estimate for the supply all the components
-119-
HtlKH WMtlMt
-mum turraa »JO
MCONOMV CCK
• U t l CO»
ri«.<i.} ICT PLAN raw
for" the ICT have baan purchased from local aourcaa. The aaoondary
Iron coraa have had to ba nade in the workshop. Tb« powar aupply i«
axpactad to be ready foe teata in January 1975.
An enalyais of tha ripple, the waveforma and tha performance of
tho ICT ia eomewhat difficult to evaluate. Only the full wave voltage
doublar circuit haa baan axaminad thua far I ' A conputar prograa waa
tharafora written to eiaulate tha behaviour of tha ICT for varloua load
ourranta. Typically, at a load currant of one allliaajpare, while tha
pa«k to peak ripple In each aecondary aupply la two par cant, tha rlppl*
for ttia antira ICT aupply ia only 0.5 par cant with an output fra-
quanoy of 300 cycle* par second. For ion implantation thia rippla
aay ba tolerable and aay awan be uaeful in obtaining a bee* raJbtei*
It aay however be eliminated by iapoalng it 300 cycle oorreetlon
algnal in entiphaee at tha high voltage terminal,
Tha heavy ion aourca, extraction and aiaaa anelyeia eyeteej fort
tha ion laplantar have been Made. The ICT aupply would then provide
-120-
the accalereting valtaga for tha analysed bean. Tha high currant
reducee tha iaplantation proceae ti*e conaiderably.
1, T.R. Bonn and A.J. Scaturro, IEEE Tranaactlona on Power Apparatueand System*, 84. (1965) 942.
2. D.L. Waidallch, Proc. I.R.t. 2£ (1941) 545.
6 . DatBMJLnatinn at target thlcknaan for thin fc«roeta, evaporated
on thick backinoa. utlllalnn hack scattering of aloha oartlclae
(H. Balakriehnan,, S. Kailae, S.S. Kerokatta and n.K. (lahta)
In th« aerlas of sxperimanta in our laboratory, uaing K , n ) and
(p,n) reactions, it hat become necaaaary to datermine absoluta crota-
eactiona to great accuraciaa. In auch naaauranenta, it Maa found
that the Major part of tha error creeps in through tha arror in datar-
•ining target thicknaaa. Hence the importance of abaoXuta datarmina-
tion of target thicknaaa can newer be owar amphaaiaad. Various aathoda
can ba adopted for target thickneaa aaaaursmsnta, lika direct weighing
or evaporating a precisely weighed quantity on to a backing kapt at
definite distance. But those methods may not be feasible in certain
caaea and ao back scattering of charged particles will be the only
possible way.
In tha preaent studies, tsnteluw was used aa tha backing Material.
Special efforta are required in the target thickneaa determination,
when the target «ass number ia leaa than that of the backing. This
problem is ainilar to that of non destructive method of investigation
of surface layers on thick substrates. Tha nethod utilises the principle
of the shift in the aharp energy profile of the back scattered low
energy charged par tic lee. Alpha perticlee ere found to be trtttar ewong
the lighter particles, since the shift observed i« relatively larger
-121-
•nd aince the •pacific ensrgy losses are accurately known.
The back acattering of aloha particles, to scattering angles of
1SS» haa bsen mads use of in determining the thickneases of about fifteen
29Si and CaF_ targota of varying thickisaaea, In the range 2.S ksV tc
30 keV for 3 PleU alphae. The technique ha» oaen made atanBifcive enough
by fcha uas of a 4000 channel analyaer and gain stabilised electronics to
meeeure thicknsssea down to about 2u,qm/cm with an error of +10$C.
Ths anBtgy ahift was obaervad for alpha particles directly buck-
acatterad from tantolua and alao after passing throuyh the target
dapoait. The point of Inflection of tha scattered energy point wa«
datarmintd uaing • least squarso computeir programme, to obtain tha
snargy ahift, but this method of determining ths energy shift solsly
from one point uiaa found to be lsaa accurate becauaa many a time,
local fluctuations in the energy profile influence the point of inflec-
tion to appear at wrong pointa. Hance average energy shift waa obtai-
ned from many corresponding points on the two parallel energy profiles
of the scattered spectrum. rig.6.1 indicates the energy shift obtained1
for 1.5 flaV, 1.6 Half and 1.7 lieU incident alpha particles scattered at
165* backward angle from a CaF, target of 3JUg«/ci* thickness.
3 J 0 0 - 1.50MeV
Ca Fj dtpostt on tontalwn backing2 5k«V tor 3MtV alphas (weighed)
(~3 *jgm / em').'. 1.7MWV
-mo
- K 0 0
- IKD
Coutgy a' . l f t r.f.t lini-rt tnr 1 .S 1.6 .jni! 1.7 ne\l (ncioenl
al(,fca p a r U t M : •rr.it(Prpd tt 165° dackinrrt iinrila
o Cflr2 Let t,i t. u( -^3 ^»cj!Vcrn2 tlilcknoPS
-122-
7, flp<; Iflla^fcion of Haematic Ti^ld mt\d HfF. in a. Atlaufchally
Field warlshle tmtay Cyclotron '(H. Ismail and A.S.
Variable Energy Cyclotron require an efficiant system foe dete*-
einlng th* multitude of Magnetic riald and r . f . aattinga naoaaaary to
produce a apaclfic ion baa* with a given energy. Tha computer progra*
r I t LOCH certiee out field trlnming calculation* uaing an itatatad laaet-
aquara prooaaa. A nodifiad laaat-aquataa f i t of tha tr la coil avaraga
field* to tha diffaranco fiald batwaan tha iaoohronoua fiald and tha
•ain Magnat averaga fiald ia parfor*ad to dataraina t r i * coil curranfee
for tha NTC aata of conoantcic circular t r i * coila. Li*itation on tha
trim coll powar aupply aca lapoaad. Tha taaulta of tha calculationa ara
ahown in Fig.7.1, whara isochronous f lald, *»in *agnat average field «nd
fit tad fields ata ahown along with tha raaulting arror fltlda in tha
intarwal ovar which tha f i t waa parforwad.
For each of tha praacrlbad aat or anargy valuaa tha E.O. coda
coaputaa tha relevant propartlea of tha equilibrium orbit and the
linear o«cillations about this orbit to aaaaaa tha *arita and defect*)
of a given median plane f ie ld. Tig.7.2 and Fig.7.3 show the celcuie-
ted rediel and axial focuaing frejuenciee, V,. and N ae a function of
average radius for the f i tted field ahown in Fig. 7 .1 . The program
then calculatee the energy Cf at which the ion would enter the deflec-
tor, aft«r making due allowance for the rediel dieplecement of the
accelerated central ray orbit «t thie point.
For a given r . f . end dee voltage, the quelity or a magnetic f ield
for acceleration purpoa.s can beat be eeeeeeed fro* the properties of
the reeultent phaee-energy vurve $ ( £ ) for the oentrrl ray trajectory.
The progra* therefors adjusts the t r i * coil currente and tha r . f . eo ee
to obtain e leaet square f i t of the^{£^ to e preacribad funct'm
-123-
1 S
i• * • *
If
n
-124-
between the Initial energy and tha choaan final energy C . Tor a
cyclotron which operates with phaae aalactlon alita in tha cantral
r.'.ion -iiid consequently achieves single turn extraction, the initial
phase spraad ^Qwithin each ion pulae will ultimately produoa a corralr*
ponding spread A £ f in the final beam cjnergy. Optimum performance
will bs achieved only whan A E f i* properly minimised. Tha program
obtained energy focusing simply by Imposing a suitable constraint within
the fitting proceaa and the resultant <D(E) curwaa coneaqusntly oaelllata
about zero. The program also chacka tha anargy stability by integrating
longitudinal notion equations to obtain, aa a function of turn number,
the shift St in tha cantral ray anargy produced by a fractional change
• £ in the r.f. Fig.7.4 ahowa the phaaa-energy curve for tha cantral
ray for tha initial field and for CD - 0*. for tha Initial fiald, I.e.,
the fitted fiald of Fig.7.1, Fig.7.6 shows tha energy spread pro-
duced by the Initial phase width ^ $ - ±2' aa a function of anargy
and Fig.7.8 shows tha energy shift produced by the ££ *+S pp» aa a
function of anargy. Application of tha above wantionad constraints
within tha program produces fialds from tha fitting process which
possess two important properties of a perfectly iaochronoua field.
Results of the above calculationa ara shown in Flge.7.5, 7.7, 7.9
for the improved fiaid. These figures show tha marked improvement
over the uncorrftrained calculation with respect to pheae-energy rela-
tion, beam focusing and beam atability properties of the beam.
Tha program la used to atudy tha design of 200 MaV cyclotron.
•Preaant addraaat Variable Cnargy Cyclotron Project, BARC,Calcutta 700 064.
-125-
ft# Thin film Scintillator Detector for Fiaalon ftiquanta
(N.N. Ajitanand and K.N. Iyengar)
Development of thin f ila scintillation detector wae undertaken
in ths Section to *eet th» need of a fiaaion Trag*ant datactot which
can give a faat tins raapunaa, can aaparata light and haavy groupa of
fragnsntr and b» inaaotltlve to radiation danaga. ' Thin fllaa of
different plastic scintillator *atariala varying in thlcknaaa fro* 2
microns to 10 miccona wata propaced by different tachniquaa. Tha
filna ware mounted directly on a photoaiultlpiiar face and thair rae-
ponaa to charged particles waa studied. Seat results ware obtained
for tha caaa deacrlbad balowi
500
400
300
I 20°ou
100.
DYNODE PULSE HEIGHT DISTRIBUTION
20 40 60 80CHANNEL NUMBER-
f i g . j . l Pulse hbijhL dlstrlbi^Hon from thu Jynudu Df thu P-fltubu fur Cf fr,»yi«unt».
-126-
A thin film of S£ 102 plastic scintlllatot was prepared directly
on to • photoMultlpi.Ler face by the evaporation technique. A solution
of the ecintillstor was f irat prepared by dieeolving about 150 Mgs of
plastic «cintiliator in 10 Ml of toluene. 0.4 ml of thia solution was
then epread on the flat Face of a 6810 A photontultiplier 1saving a
fairly uniforn and clean fiJ,* or the scintilla tor of about 'i Microns
thicknsaa. The photonuiJitipller tube was than Mounted in • vacuum
252chamber and a Cf source waa pieced at a distance of 3 on froM tie
ecintilistor. The faesi of the photomultipller tube waa colli«ated with
an aluminium plate ao that only the central portion of 2 CM diameter
could be seen by the source. The tube wee operated at an anode voltage
of 2000 volts and on optimum focussing voltage of 250 volts. The charged
500
A 00
I 300 -
zo 200o
too -
ANODE PULSE HEIGHT DISTRIBUTION
20 40 60 B0CHANNEL NUMBER
100 120
rig.5.2 ' Pulse height distribution from the anude of th»tub* for C f " fragments.
-127-
particles from the eource ljat a small portion of their energy in the
thin film thereby exciting acintillationa which cauaad electron Mission
in the photo cathode of the photomuitiplior tube. The pulac height dis-
tribution of the pulses from the anode and dynode are shown in the 51-62
figures, Ths haauy and light fragment peaka are well aaparatad but tha
separation of the fragment pulaoa from the pulaea due to tha natural
alphas and the noisa of the photomultipliar tubs ia not very good.
The anode pulse height aaturataa for the highest energy fragment*
producing a distortion of the l'.ght fragment peak. By reducing the
thiokneaa of the scintillator film and coating it with a thin reflec-
ting layer of aluminium or eilvsr it is expected that a batter itepa-
ratlon of tha fragment pulaea from tha natural alph* pulaee can ba
achieved.
Further work in mounting tha films in a transmission geometry
ror certain special applications is being carried out.
9. Development of a nulfcl-parawater data acquisition system
(8.R. Ballel, P»N. flama Rao, S.L. Raote and S.K. Ketaria)
Tha development work has bean carried out on the existing multi-
parameter data acquisition system to increase the number of parameters
from four to six for carrying out exhauative experimental studies in
nuclear fission. An interface using integrated circulte has bean
fabricated to record the pulse height information of the six parameters
from alx independent AOC units, event by uvent on to an incremnntal
dlgitalmagnatic tape recorder. The interface ran selectively uee the
*u.ltipcrameter in two, four or six parameter *»da with a maximum count-
-128-
lng rata of 120 avanta to 40 svente pat aaconda reepectlvely. Tha
recorded data la in standard codn on ? track magnetic tapa and it can
ba eonveniantly analyaad off-lino.
In ordar to be abla to do calibration and routlna checking of tha
aix para«atar data acquisition syatam, tha read out facility ia alao
baing davalopad. With the raad nut interface unit tha elngla pulaa
height distribution* of mil the eix parameter* can ba displayed slmulta<
naoualy on the display unit of tha TrtC multichannel analyser. This
readout facility it more versatile than the earlier ona in use. The
interface unit is under fabrication and parts are being tasted.
10. X-ray apBCtrometry with Si(t.l) Systems (dadan Lai, S.K. Katarla
and S.S. Kapoor)
Semiconductor detector Si(li.) X-ray fluorescence spectrometere are
being progressively used for rapid Material analysis. The energy reso-
lution of these systems play very crucial part for analysing tha X-ray
spectra from adjacent slaments, in particular for lighter elemanta. In
tha paat, the element analysis work was baing carried out by u» using «
system with energy resolution of 385 eU at 6.4 kaV. Further develop-
ment work carried out has resulted in the improvement of tha system
energy resolution to 270 aV at 6.4 keV. Tha schematic of tha modified
detector mount used in this system ia shown in Flg.TJt, Tha present
deeign ensures better cooling of Si(Li) detector, minimisation of the
microphonics and stray input capacitance.
-129-
HOLDER-
N
-SI (LI ) DETECTOR
•FET
-COLO FINGER
FK3. 1: SCHEMATIC ARRANGEMENT OFDETECTOR AND FET MOUNT
ri«.7.t 5th«»atie airangHmwnt of 6i(H) d«t»e».ot and ft f mount.
X-RAV SPECTRUM OF A STAINLESS STEEL SAMPLE. EXCITATION RADIOISOTCPE: 1,125
5000
CHANNEL NUMBER
Tig.7.2 X-ray tpuctrua^f a Stainl«s» otcol simple with BKcitatlont«dioi»uto^o 1
-131-
The FET input preamplifier P120 uaed in thia system employs drain
feed-back Instead of normal resistive feedback, eliminating the noiaa
contribution of the feedback raaiator. Thia furthar raducaa tha atcay
input capacitance. Tha praaant work haa bean carrlad out in collabo-
ration with tha Nuclear Instrumentation Ssctlon of Electronics Division
Mho haw* contributed towards preamplifier design and FET selection.
The spectrometer is being used for X-ray fluoraecenca analysis with
radio-iaotope for exciting tha charactaristlc X-raya in tha sa«pls. A
typical spectrow of a ateal sample is shown in Fig.72. Tha radloisotopea
1 2 5I, 241Am, 155Cd, 55Fe and 238Pu have been uaad for optisjue) axcitatlon
of diffarsnt samples. Tha quantitative analysis has bean carriad out
for synthetic samples minerals and various induatrial samples using
thick and thin sample tachniquaa. The different procaduraa for quanti-
2tativa analysis have been developed.
The knowhow generated in the Section on tha fabrication of high resolution
Si(U) X-ray spectrometers and its application for the X-ray fluorescence
analysis is being transferred to £C1L, Hyderabad for the fabrication of
such syetBfiie on a commercial basis.
1 . Clad transactions
2. l"!adan Lai , fl.Sc. Thesis (1975) Bombay
-132-
M . QnurlPDiiBnt of a Nondastrucfci.ua Taatinn Tool jaaaad an 'Double
Saionmct Hnnhiuif Spacfcrnacnpy' t*ORCf105") for tha Haaaura*
•ant of Rasldu^l Surfac«« Straaaaa (K.R.P.n. Rao and
P.K. Iyengar)
A nondestructive aethod of eetiaation of ths Magnitude of
residual surface atraaa and determination of tha nature of tfta strsss
(i.e. whether it ia coapreeelve or teneile) la or vital importance in
the ateal induetry particularly for joba which ara subjected to
atraaaea in aarvica. If tha atraaa ia in tha aa«e direction aa that
•ncountarad in service, and exceeds a certain critical lia.lt, than
tha Job can crack. Tha feaeibillty of utilizing noaaoauer apaotroacopy
aa a nondestructive teetino tool baaad on a double resonance phenomenon
wae anwieeged and tha apactroaetar haa baan fsbricated. A eoheaatic
dlagraa cf tha epaotroaefcar la ahown in Fiq. 9.1. Tha principle
involved in the aaaaureasnt or reeidual eurfeca atreaaaa la aa followa.
The source, SR i» aovad with an appropriate constant Oopplar Velocity
such that only one of the nuclear levels in tha ground state cf tha
•catterer is excitedt and thua a virtual aourca Stf in the aoatterer ie
created. Tha radiation eaittad froa tha virtual aourca Sv ia allowed
to paee through a standard single line absorber snd than they are
counted in a special 2IT toroidal counter. Tha absorber ia aovad with
an appropriate velocity W1 ( Vj) euch that tha Oopplar velocity corres-
ponds tp the position of maximum alope A(B) of the abaorption epectrua.
Now if a atreaa ia «pplisd to the acattarar, (spaclcsn) tha whole
absorption U n a will shirt in one direction or the other depending on
tha nature of tha atraas (i.e. whether it la tensila or coaprassive).
Thle saell shift will rssult in a larger change in the abaorption count
rate, &H. ( £ > O and thle change in count rate will b« proportional
to tha atraaa applied. For batter asnsitivity, u ctri define a para*
-133-
rtttSSBAUER DRIVE MbSSBAUER DRIVEI It
2 IT-TOROIDAL COUNTER
Sv«WHTUAL SOURCEIN THE SCA1TERER
Vt
S« • SOURCE ATTACHEDTO DRIVE I
NUCLEAR LEVELSIN THE SCATTERER
DOPPLER VEIOCITV
STANDARD ABSORBERATTACHED TO DRWE I I
r i g . 9 . 1 A Kch«3i«ytln diagram of thM doublB resonance nnashouor opoctiu-»Btpr for thu muonutement nf residual sutfot.e str»5S89.
-134-
«eter y = and this L will be proportional to the appliedL 2.NO
stress £ . Tor any given material, us hava to first obtain a cali-
bration curve for the relation between ^ snd t h 6 stress G applied.
Once thtt relationship between >V and t is established the nature
and magnitude of any residual surface stress on any bulk material made
up of the same material ae the specimen can easily be dsturitinacS.
Individual Ptossbausr drives and t»ie special tarodial proportional
counter have been tested. The Mechanical assembly of the whole spectro-
meter was also-completed and tested for alignment. Testing the double
resonance spectrometer is currently under progress.
12. leaser Raman Spectrometer fW.L. flantsl, T.ft. Rao, V.C. Sahni
and *.P. «oy)
An earlier report described the principal design fsaturea of •
Laser Raman Spectrometer, the fabrication of which has bean undertaken
in our Division. The Reman scactered signal from 'the sanple is
spectrally analysed by the double monochromator and it forms the crucial
part of the spectrometer.
This instrument, which employs the Czerny - Turner mounting of
the gratings and mirrors and a cosecant driva for linear wave-number
scanning, has been fabricated (Fig.10.1) and extensively tested. The
double monochromator was calibrated using • neon spectral lamp. Tha
spectrum wss recorded using the photon-counting syotem in tha analogue
mode at a scan speed of 3C
of SO microns (Fig.10.2),
mode at a scan speed of 30 cm /min. with entrance and exit slit widths
( iii. 10.1 Upper picture gives a complete view oft he Raman Spectrometer anvj the lowerone shows the la you I ol'ihc opt ic;i I Loniponenls in the double tnnnoehromator.
-135-
I 7. *
-1S t 'rSTs8
' . . - < V ) i " M . .
01
11
ZZJ. ._.§.,
-136-
Tho tracking of tha grating* was round satisfactory as
from tha Intensity of tha apectrai lines over a range ut 23000 - 14500
CM" • Lines occuring 3 Cn~ apart are clearly resolved by the instru-
ment. Tha reproduciblllty of tha instrument was found to be within
£ 0.5 Cm" . In tha ranga 21000 - 14500 Cm" , the absolute wavenumbur
indicator is linear to within +. 2 CM" . This covers the useful ?anga
of Ar and He-Na lasers. However, in tha ranga 23000 - 21000 Cm" ,
tha departure from linearity is More and this seaa to arise fro« non-
uniformity of the lead screw in that region. Tha •ample chamber,
focusing and collecting optics system are being fabricated.
1. BAflC - 768, Annual Report of Nuclear Phyaics Division (1974), p. 166,
13. Fabry Perot Spectrometer (K. Usha Osniz, P.S, Parvathanathan and
M.S. Paranjpe) •
A Fabry Perot epectroneter ttas bean constructed for studying
Brlllouin scattering. A schematic diagram of the spectrometer is
shown in Fig.11,1, Ths light »ourc« is s Hs-Me laser, giving a light
of wavelength (^) equal to 6328A. The laser beam falls on tha Mirror
H, Mounted on an optioal bench and is reflected on to the ssnple. The
direction of incidence of tha light bsa» can be changed by MO veing the
Mirror along ths optical bench. The dielectric coating of tha Mirror
!• such that it transmits 10 to 20 percent of ths incident b»aM, and
the tranamitted beam is detected by a photodlode which servos as •
laser pows; monitor. Ths reflected beam la focussed on to tha •••pie
by lens L1. Tha light scattered by ths sample passes through • circular
FA3RV PEROT SPECTROMETER
' - ' • • ' . > < • . ' ' • •
r i j .11,1 A schaaatjc diagraa or the FabryParot apectronstsr. f i g . 1 1 . 2 A cutaway figure of tha faory Pergt
in ta t ! arometar « i th l t a housing.( ' ; nicroc houalng, {?) Hirror ,( 3 ) Invar spacer, (4 ) Sprlng^loadedaligning tcran, ( 5 ) Lawulling acraw,\6) Fl .ad base, ( ? ) Sliding baa«,(S) Lvacuatad apaca for haat insula-t i o n , ( 9 ) Outar houalng (?0) Endriang«
-138-
•perturs A , which limits the solid angle of the scattered beam seen
by lens I,,.* A parallal beam of light emerges from ians L. (Since it*
focua la at the aaapla centre) and entera thu Fabry Psrot cavity. The
direction of the axis of this cavity fixes the scattered beam direction.
Tha range of scattering angles that can be scanned in tha present
geometry Is from 36* to 145*. It is hoped to extend thia range (in
order to study small angle scattering) by tha use of an additional
nirror.
Tha pressure scanned Fabry Perit interferometer (FPI) analyses
the scattered baa* spsctrum. Oetails of the fPI are given in Tig.11.2.
The Fabry Perot Mir cor substrates made of fused ellica art flat to
^/IQO on the first race, which is dielectric coated to givs 98%
reflectivity it X > 6328 *. Tha second face lm flat to ">*. /ZO and
is coated for antirsflection at the sama wavelength. The optical
length of the Fabry Perot cavity is defined by the invar epacera
between tha mirrors and by the pressure of the nitrogen gas in this
cavity. With tha use of suitable invar spacers, fre« spectral ranges
9 11
between 10 Hz and 10 Hz can bs obtained. Tha resolution width of
the interferometer is expected to be about 5 x 1 0 Hz for a frea spectral
range of 10 Hz. Tha three spring-loaded screws at one end of tha
mirror housing enabla one to align the mirrors accurately. Tha Mirror
housing is provided with levelling screws which rest on a sliding base*
This base is provided for rough alignment of the FPI outside its
housing. The space between this housing and the outer housing can bs
evacuated so that tha temperature within the interferometer can ba
maintained fairly constant. Windows made of borofcilicats ylsaa (flat
-139-
to ^ /5 on both faces) are mounted on the two und flangus. The
housing containing tha fPI is mount ad on a base which allows a lateral
•nd a rotational movement of the FPI, in ordar to align it with reepoct
to tha scattered light beam. A gas ltiak system connected to the fPI
ensures that the pressure of the nitrogen gas in the Fabry Perot
cavity increases linearly with time, which in turn ensures that the
pressure of the nitrogen gas in the Fabry Perot cavity Increases
linearly with tine, uhlch in turn ensure* that the frequency scan of
the scattered spectrum la linear in tins.
A series of concantric interference ringa ore produced by the
FPI of which tha central one is I'ocussed by lens L, (Fig. 11 .1 } on to
a small circular aperture A,. Tha light passing through A. pauses
through a light guide and is detected by a photomultiplier (9658A).
Tha light guide condenses the light on to a small apot (or 3 MM diameter)
at the centre of tha photomultiplier face. The photcmultipller Is
housed in a liquid nitrogen cryostat so that the temperature of th«
photocathode can be decreased to about - 60*C by radiation cooling, in
order to reduce the dark current. It is found that a reduction of a
factor of 100 is obtained in the dark current if ths photocathode is
cooled to -20°C. The Magnetic dsfocuaaing arrangement used along witn
the light guide also helps to increase tha signal to noisa ratio of the
PCI tube by a factor of 50. The output of tha photomultiplier ia fed
either to a DC amplifier or to a pulse amplifier (depending on ths
Intensity of the signal) and their output Is fed to a chart recorder.
Jith the FPI finesse being ^ SO Brillouin scattering mainly
from fluids, is expected to be studied with this spectrometer.
1. K. Ueha Daniz, A.S. Paranjpe and P.S. Parvathansthan, BAHC-694
Annual Report of the Nuclear Physics Division (1973), p. 1*8
-140-
Bf""" n<ffractlon (A.H. tfenkatesh end «ao)
Whit* beam diffraction studies using ths triple axis neutron
spectrometer were continued1. Diffraction pattern* frow Silicon powder
at scattering angles of 32* and 49* have been obtained using Cu (200)
analyser (Fig.12.1). Qualitatively, these .-e similar to ti»e-of-flight
diffraction patterns patterns obtained by Bures et al . Diffraction
petterne of bath Si and KC1 have aleo been obtained using Re (1120)
snsiyesr {tig.la.2). The purpose of the latter experiment «s« to
CM (200) ANALV!>f.R
SI
*NALYSEfl ANGLE Bd I
.. L. J— L - J - ..I. ...J. .. I — I—It. H I i.» l« ?n
WAVKIENGTHI*")
U l f f t i i c t l u n patterns or b>lpoudur obtained at acnl tur -intj angles of S2" and 6<)°,»• doaurVBtf by Cu(2UU) an«-i / s e t , in thd uhl t« busmt er.hniqut*.
ANAIVSEH ANOLC * . (0C0)
0* 01" oi to uVfftVELEMOTH if)
U
f i g . 12.2 Thu whitu huam n,,Hi_trnoi(inculirtrunt ly itMtturtdby a puriiunx s.implii ), anjI hu diffraction iiiitivrnsuf Sil and KC1 povfinrs obtili-nutl at Iho s<:ui.lHring tinyl*of Ji: ' , as uiibuivud byB(( l i7u) .lci.iiyii.jr. In ttinwhite b din technique.
I o f V > ft )r2*hkl <*- Z_- — — hkl hkl a
-141-
asseaa potentiality of «e (1120) as an analyser, in vitiw of ita high
reflectivity and other desirable properties.
Analysis of tha diffraction patterns were carried out uilng the
expression
—S i n tj>
where I,., is thu intensity of neutron* Bragg acattered at an angle j
from (hkl) planea in tha powder, P^ , the Multiplicity, Fj\, the
«>2wstructure factor, e hkl the Debye-Uall.er factor aaaociated with tha
(hkl) planea. (7) ( X } la the incident neutron flux on tha sample,
R ( X ) the reflectivity of tha analyser plane, ^ ( A ) ths africiency
of detector, T ( V ) correction factor for absorption in tha sample
at tha wavelength X ( - 2d.sin8.). Correction for extinction in the
analyaer la not considered.
Assuming a Claxwellian apectrun for (|> ("X) and that R ( X ) is
given by
•In 2 @ A
(where N is tha reciprocal unit call volume, F^ the structure factor for
the analysing plane, a~ WA the corresponding Oebye-Ualler Factor,
^ the mosaic spread, U. - linear absorption coefficient and 2 ^ .
the scattering angle at the analyser), one can calculate I ,.
Table I gives I , the experimentally measured intenoity and
c
1 , the calculated intensity for various reflections in KCi and Si
using tne two analysers at u) - 32* and (J) • 49". Tha inten-
sities are normalised to each other at a 'suitable' reflection.C n
It is observed that tha agreement between I and I for all reflectionsis qualitatively satisfactory. Large differences ars seen for a
few reflectiona and these are due to uncart air? t ies in t-.he estimation
TA8LC 1 Pleasurad and Calculated In tens i t ies of K.C1 ana t>i Analysed at ScatteringAngles of 32° and 49° by CJ (200) and 8B (1120) Crystal Analysers in tnsUnite Beam Qi f f rac t ion Technique.
h k l
44 2%600%531
4 4 0
333+511
4 2 2
331+420*
4 00
222
311
2 20
220
111
(«4.2)2+(600)2+(53)2
(333 ) 2 +(51 i ) 2
(422J2
(420)2+(331)2
KC l
n
--
7
22
S
29*
1 9 *
128
148
4 0
-
-
-
f =32°
--
5
24
10
35
63
128
126
91
-
-
-
Cu(2C0)KCl %
15
2
2 1 *
2 1 *
139
2 8 *
51
25*
1 0 0
28
-
8
•18
15
13
Analvser=4 go
I c
30
11
18
50
116
28
52
80
100
55
-
7
6
13
31
i "
m
-
-
2
7
-
25
5 3 *
-
130
-
-
-
=32"
-
-
-
4
5
-
47
114
-
130
-
-
-
Si fI*
-
7
13
2 3 *
1 8 *
-
5 9 *
3 9 *
-
-
9*
1
9
i
=4S«
I C
-
11
25
24
18
-
64
87
-
-
1
3
6
Bed lKCl 9=
-
2
6
21
14
38*
3 1 *
157
-
-
-
-
2 0 )32°-Ci
-
3
S
38
15
47
83
157
-
-
-
-
-
Si <£=32°
l " 1 =
-
2 2
7 =
5 6
-
60 60
176* 146
-
-
-
-
-
-p.no
+ abaant in Si
* affected by doutjla Bragg Scattering.
-143-
•f the incoherent background from th« sample but principally due to
double Bragg scattering effects in tha analyser. Tha reflectiona
that are affected by tha latter are Indicated by an asterisk in the
table., The •effective' apactcun fro* Be (1120) ahown in Fig.i?,2(«)
indicates structure due to double Bragg acattering (tha structure 1:
mote than in case of Cu (200)). Ule believe therefore that choica of
a auitable analyaer plane and its orientation to be free fro* double
Bragg scattering is crucial to obtain quantitative agreement between
n CI and 1 . Studies using G B ( 1 1 1 ) will be taken up in tha future.
1. K.ft. Rao and A.H. Venkatesh, BAHC - 768 Annual Report of theNuclear Physics Division (1974), p. 173.
2. B. Buras, J. lacisjewicz, Id. Nitc, I. Sosnowska, 3. Sosnowskiand F. Shapiro, Nukleonika £, 523 (1964).
15. Thq Multiplane Analyser (P.P. Chandra, d.L. Thaper and
B.A. Qasannacharya)
In an earlier report we had calculated the reflectivities
of various single crystals in 'multiplane* geometry. These cal-
culations were performed with crystals having a mosaic of 10
minutes of arc and were confined to the situation whan the bean is
incident along tha (jDOIj direction. This gives a multiplicity of
6 for hexagonal crystals and 4 for the cubic crystals. It was found
that for the backward angles the multiplane geometry gave an enhance-
ment factor of about 2 over the single plane case. These calculations
heva now bean extended for cubic crystals with the incident bea*
along |jM G (thrae fold multiplicity) and \jto} (two fold «ulti-
-144-
Tabla I
Description of thaocetlcally calculated peak and Integratedreflectivities of various crystal* In both of tha geometries(sea text) and tha parameters required therein.
Thickness of tha crystala • 0.5 cms.Mosaic apraad of tha crystals • 10 Minutes of an arc.
Crystal (hkl) (As) 20
Single plana casaMultiplane c«a« Transmission Reflection
.max .•ax Remark
Pb (331) 2.207 153.5 73.8 12.37 49.3 11.51 48.6 7.62 IncidentbesM along
Cu (331) 1.611 78.9 10.82 23.9 4.71 59.8 7.59 Qio] |Multiplicity.
Ge (331) 2.522 79.1 16.33 34.0 9.98 57.1 10.92 Two
Pb (113) 2.593 83.8 43.15
Cu ( 1 1 3 ) 1.694 121.0 77.6 31.56
Ga (113) 2.964 76.8 48.00
Pb (133) 2.102 70.2 18.59
Cu (133) 1.535 136.0 73.1 1S.63
G» (133) 2.403 74.2 24.06
Ge (224) 2.174 141.0 84.5 23.64
48.8 39.17 53.4 40.52 Incidentbea» along
35.5 17.10 60.8 20.59 Qi 1 fj %h
41.6 28.76 56.4 30.37 city > Three
>6.4 13.65 35.6 a.58
31.8 8.31 47.9 9.17
39.1 14.91 44.4 12.88
38.3 13.25 54.9 13.39
Rm«x 1 ( ( t M p - > k fgfinctlvlty In percentage.
R is the integrated reflectivity in (A* Minutea).
-145-
pllclty} direction. The effect of changing the mosaic aprsad on
crystal raflectivitias haa also bean investigated.
Computation with the values of mosaic spread of 5' and 3* shows
that the gain in the reflattlvity of the multiplane ayeta* over the
single plane CBBB la not very different from that obtained with tha
mosaic spread of 1C1' (reported earlior ). Tha results of tha
calculation!) for ths beam directions elony y i 1 j Jnc' (*10J *n
some cubic crystal* are summarised in Table I. Theae yield a gain
factor of about 1.5.
1. P.P. Chandra and 6.A. Uasannacharya, BrtflC-766, Annual Report ofNuclear Phyaica Oivlaion (1974), p. 177.
16. frsuuancv Counter (S.S. Srinivasan)
A simple frequency counter 1B developed using Integrated
Circuits. A 10 KHz crystal oscillator is used to give a 0.1 sec
or 1 aec atandard gate for sampling the input.unknown frequency.
Flip flops FF 1 and FF 2 are used in programmable manner to
give automatic sampling after a reset pulse is given to fF 1. This
reset can be given either manually or automatically every three
9acond« by further scaling the crystal oscillator. Flva digit
Nixie display is provided to read the unknown frequency. The unit
has itR own power supply of 140 UUC and 5 UDC. Fig.14.1ahowa the
layout of the frequency counter. This instrument is used for con-
tinuous monitoring of ths radio frequency used in a polarised neutron
spuctrometer. The accuracy of the instrument is 1 in 10 per second.
RECTCUNG FREQUENCY COUNTER
SCALEOF TEN71 SO
10 KM 2
CRYSTAL
DSC&UttOR
\lHlU
SCALEOF TEN
SCALEOf TEN
T19C
SCALEOF TEN
t.NIXIE a i s r u r* j i : i
-fi-eri
-147-
17. H Pauar Punch-Tape Facility for the 1 D^d Channal-Analvn..
(4.5. Oeshpande)
Provision has been made in the 1024 channel (Hungarian
5126) analyser to punch the data on a Five channel paper tap.
Binary outputs are brought-out for punching data, flaking uas of
this output' an inter-face has been developed to punch tha data on
• "Creed" tape punch unit.
After tha "start tape punch command" from the analyser, ths
moat significant digit la punched on tha paper tape. At tha and of
each punch a rBturn pulse which is generated in the interface is fed
back to tha analyser. This pulse causes the content .1- tha dacada
to shift the punching operation to thn next moat significant digit.
After punching all tha digits (in this case it is five digits) the
"and of word" signal, which is generated in ths analyser, is also
punched. The next channel is than selected and tha sans operation
repeated. At the end of last channel of tha selected memory, tha
punching function stops automatically within the analyser.
In tha multichannel analyser even parity is generated. In
the interface unit an inverter is put to have an odd parity. Craad
taps punch unit which ia used hare la a five channel unit which
punches upto 30 characters per second*
To follow tha correct sequence several delays sre wired and
pulses are shaped for correct width through unlvlbrators.
Ths trip relay pulse which punches the information and
advances the papar tape is of six milliseconds duration and is
obtained from the start pulse Itself after a delay of approximately
five millleeconda which ia roughly tha time required for the
-148-
•eicction of the appropriate cod*. Tha raturn pulse, which indicatse
the end of punch operation, la generated after 40 milliseconde with
respect to the arrival of the atart pulae. Simple driver clrcuita
aro wired to actuate tha coda and parity relays.
18• Ccptrol System for the Hultlara Tripla Aicia Spactroasatar
(P.H. Vijayaraghavan)
Tha multiarni tripla axia spectrometer haa nine positional
aettinga to be controlled in a programmable fashion. Of theae
eight are angular aettinga and tha ninth la tha facility for back-
ground measurement. Theae parameters to be controlled are mad*
available in digital for* using digitiaara. A control ayete*
capable of handling all theae nine piecea of Information haa bean
put into operation. The work waa taken up in collaboration with
the Electronic* Oivialon, BARC.
The system UBB« a five channel punched papsr taps si input.
The paramstars are labelled 1 through 9 and the position* to which
thsy have to be changed are read in from the papar tape, at ona
stretch. A typical input ia ahown below
• L, A, B, C, 01 E.,, t2 »2 B2 C2 D 2 Ej. ate etc -
The symbol •+• danotaa the atart of data. I., L. etc. ara tha
labala and the string of five digit* ABCOE danotea tha angle to
which the corresponding labelled aetting haa to ba aoved. Two
euccesalve pieces of information are separated by a comma. This
-149-
control information can be in any order and there only be as many
bits of information as are to bs controlled. The sign •-' denotes
the snd of data input.
Trus input data is stored in a bank of nina control data
ley is tor s (LOti). Corresponding to each one of the parameters there
is an absolute position register (APH), un completion of the input
data an internal scanning is started. Comparison is made between
the COH and APH of a particular lable and the difference signal
with the appropriate sign is generated. The driving mechanism is
activated in the required direction. The APrt keeps track of th«
current angular position from the pulees received from a digitiser.
Equality between the COR and APrt for a particular parameter stops
the driving mechanism.
The process of comparison is carried out in a Centralised
Comparator which is tine shared by all the nina registers. Link to
the comparator is provided through a multiplexor system.
A request display to show the status of ono particular para-
aeter at a time is also provider*. Provision for manual input at
the control panel is also provided.
1»• Large Bismuth Crystal for Increased Neutron Transmission of Low
Cnerov Neutrons (H.R.L.N. lYirthy)
Preparation and growth of large singlB crystals of bismuth
for increased neutron transmission has been taken up in collaboration
with Purs Materials Section of Chemistry division, BARC. Brldgnan
-150-
techniijue ia employed in growing the crystal. Zone refined grade
bi6muth placed In a pyrex tube uilh a constriction at the bottom was
kept stationary under vacuum while the oiuffla furnace was moved. Th»
first bismuth crystal which has been successfully grown has dimensions
15 cm in length and 4 cm in diameter. Ths measured values of neutron
transmission for this crystal are 60,4 at 4A and 4# at 1.2A.
20. Tltanlua Zirconium Alloy Caoeulea tp facilitata Neutron
Scattering Studies at High, Pressures (H.R.L.N. Nurthy )
Praparation of Ti Zrrl ,„ alloy, a null-.iatrix for nautrons,U.O& U.Jo
to bo used as container for neutron scattering etudias at high
pressures (1U to 12 kbar) ha* bean taken up in collaboration with
Atonic Fuel* Division. 5 kg of titanium and an appropriate -aunt of
zirconium corresponding to Tl Zr , of 99.9Jt purity in ?0.62 0.38
for* of ingots has been usad as starting materials.
The first phas^ consists of the three oparatlont
1. Coapacting the 10 kg charge into blilata of 6" in length. 2, Electron
beam weilding the billets to form roda of 90 c« in length. 3. Consumable
electrode melting. The second phase includes machining the ingots,
extruding into rods of 90 cm in length and melting it for second time to
ensure homogenity. All these operations were completed end the alloy
is read/ for machining into the desired shape.
-151-
21. Praparatjnir of «llowm «ne) CflpaUPil* f*-H-L-*>- flgrthy)
A* a r i rst step in instal l ing a fa* furnace fac l l l t i aa far
tha necessary hast treatment and malting, «n annealing fuinaca hae
bean buil t and is being usud. Sawaral annealing and sintering treat-
have bean aade using this f a c i l i t y . In view of tha fact that
tha furnace has two winding* (kanthal A1 wire) which can ba operated
continuously, uptc 1000'C with a temperature gradient of 30*C cm"
i t can alao be u»8d to grow aingla crystala by Bridgaian technique.
• few alloys such ae Fe.fto Z r ^ where K • 0.15, 0.25, 0.40
and 0.60 and ThCO-Fa, fere prepared for floaabauar and neutron aeattar*
ing studies. ZnCrFe.O. and Na_ .La , F e . , 0 , o ware prepared employing
th» usual sintering tschniquss.
Compounds si.ch aa Te N and CoO ""0. where x « 0.25, 0.50 and
0.?5 haws bean preparod in collaboration with Pura VtsrJals Section
of Chamistry Oiwision, BARC.
4K purity iron powder waa treated with anaonl* at SOO'C for
3 hrs. Tha resulting powder, a Mixture of Fe N and Fe-N was heat
treated in vacuum, at 450*C. This procedure which has beao standardly 1
after ssweral t r i a l runa hai yielded Fa4N with less than i% of Fa^H
phase.
Single crystala of ttira.C^ and VIC have been attempted aoploying
flux technique in nicrowaua Cngin««ring Section of UFR. A new flun
rtanely V^ waa tr ied out. while the N l F e ^ cryst.il grown in the f i r s t
attempt is aaall (1 mat cube) ths YtC crystal Is adequate for nout' n
diffract ion studies.
-152-
In continuation with the programing ' of preparing alloy * Ing la
crystals of some semiconducting materials, single cryatal of • tarnary
alloy Pb.. .Sn,, oSe, !ies been yrown. Thia work «a» taken up in
collaboration witn Pura Materials Section of Chamiatry Division, B*HC.
Growth of single crystals of this alloy of other composition ara In
progresB.
1. BAHC 694, Annual Heport of Nuclear Phys'ice 0iwiaion(1973), p.148.
22. Program 'Fourar' (R. Chakravarty)
Thla program la written to calculate ieo-epin deneity contouca
atarting fro* the Magnetic atructure factora. Thia is a Modified
uoraion of the fouxler prosra* 'FOftOAP' (by A. Ztlkin).
The apin density or Magnetic aoasnt danaity at * givan point
in the magnetic unit cell la alnply a rourier SUM of the Magnetic
atruLturo amplitude* (sa e.g., obtained froa mn analysis of polariaa<J
neutron data). The iao-dennity contouri ara calculated in aactiona
parpendlculai to the choatn direction and about the chosen origin
(usually an atoa poaition). Tha isodentity points are obtalnad at a
choaan angular interval and tha corresponding coordinates (radial
distance and angls) are printed out in tha output. The density
interval between the contoura la needed aa an input aa alao the
•yMneC y information. Ther* la provision to Maka the deneity interval
taali.«r in tha low dsnaity regions.
-153-
23. Tandem Accelerator (fl.G. Betigeri, T.P. David, C.V. Reyarappan and
M.S. Ohatle).
The utrk on 2 HV Tandem accelerator ia making ataady prograaa.
Tha first stage at tha accelerator, namely, tha ion aourca ia raady* Tha
Duo plcemetron ion aourca complete with extraction system and Einzel lana
haa b«en work!no satisfactorily. Wa have axtracted SmA N , 3mA A and
10*A H+ beams at 20 keV extraction woltega. By displacing the intermediate
electrode axle with reapact to tha ion emission apartura, wa hava
axttactad 200 itA N** beam directly. Cnlttanca and Brightneas naaauramenta
hava baan made for the ian aourca. Emittanca £ * 3.66 x 10 (e>«-a)rad)
Brigh.tnaaa B • 10>0 («A/c«2~ rad2>
In tha second atage, nawely tha voltaga generator, aoMa of the hardware
going into it haa bean fabricatad. All the component* (like gradient bar.,
epark gspa) that go to wake up column eectione have been received end fit tod
in piece, The hocpe on the •quipotantlal planes have been Made in two
plec«e. One half ia welded on tu the aluninlu* plate. Tha other half ia to
be push fitted on to the welded nection and ia held in poeition by rivetted
clips. The tank houalng the voltage generetor haa now been completely
designed and ia to be fabricated in tha Central Uorkahop. Fabrication
drawings ars being prepared, for tha charging syatam, we have alreedy
received a special "inverted motor" designed and built by Clectricel Works
Section of BARC. The motor performance on initial testa has been found te be
satisfactory to give the deeigned out put of 1*5 H«P* A eanple nylon belt
received haa been teeted for mechanical strength setisfsctorily.
The third stage of the accelerstor namely the ion optics components
haa been completely designed. This etege coneiste of (1) accelerating tub*
-154-
2) Ion aeurca aagnat 3) Analysing aagnat 4) Lanaaa. float' af tha olaaa ringa
h«va b99i* racalvad and hava baan aant tot fwrkhar grinding ta • N « B | ahapa
•no! alza aa par our daaign* Tha 20* - lam courca aagnat la balng fabrleafcatf
in tha Cantral Workshop. Oaaignftng of 30* analyalng aagnct and Clmal lanaaa
hava baen eowplafcad.
-155-
TEACHIHG AND TBAIHING ACTIVITIES
Aa in the pcavloua yaara, tha »aabara of iha 01viaion hava
partlolpatad In tha Taachlng Programta of tha B.A.R.C. Training School.
In addition, vacation Training for tha National Sclanea Talant Saareh
Scholar* and a refresher oouraa for tha Post Graduata Solanca Taachara
fro* warioo" univaraltlaa wera alao organiaad. About 30 NSTS acholara
and 14 poat graduata taaehara partieipatad. Thaaa prograa*aa consist«cl
of I
a) locturea on ganeral and apaclallaad topiea
b) individual projactt undat tha guldanoa of tha aaabara of
tha Oiviaion.
c) oanonatraticn axpariaenta
d) Viaita ta various laboratoriua in BARC and TIFR
a) ecraaning of filoa on topiea of intaraat in phy«ioa
f) quiz aaaaiona.
patella of lacturei and Couraaa Oalivecad toy tha Oiviaional
Sta ff Hmbni
Shrl K..W. Bhagwat
Or. A.K. Jain
ShrX SiK. Kataria
Shrl n. Prakaah
Shri V»C. fiakhscha
Or. *.'P»
Or. V.C*
Or. R* Subraaaniam
Shrl C.L. Thaper
Or. C.V.K. Bab*
Shri K.V. Bhagwat
Shti K. Chandramoleshwat
Dr.. A«A*
T0£i£
•Classical flechsnics
Rpi-arkt
•Elementary m rischenic3
Physics"
A?f»i»ncsd Sol.J-'
•Tr'-j.f =.M-T I3=:rngs end ftaterle.1 Sciencs*
"Gvi^rsl !•-. trcduction to Kuclc?-? Physios
•Quant•<% ^schariicB"
•fast Ras-rtors"
Reactions'4
To t-r.' '6ASC Ti .
:f the• o l .
- C ' ; • •
• c1; -
To tha Pc3t-G.T, iiTeachers cf i.'n KafreahsrCoursa, 1974.
- do -
• do -
- do -
in
Or.
lacturar
. 3aln
Or. *«K. Jain
Or. 6.K. 3«in
Sbri S.K. K«tuit
Shri Hadan L«l
Or. L* Aadtiav Rao
Or. «.S
Or. K.R. Has
Or. A .P. Roy
Dr. V.C. Sahni
Or. ft. Subraaaniaa
Topic
"kuclaar Forcaa"
"Kcc«lar*tora*
•3i{Li ) eJatactor X-ccyriuoreccanea*
"Counting Statiatisa"
"Gsnaral Introduction toSolid Stata Phyalcw*
"Elactron Stataa in Cryataia"
"Syaaatry of Cryataia"
"Quantua flechanica*
To th» Post-Craduata Taacharaof ths Refr«shar Ccvussa, 19?*,
- do •
- tia —
- do -
Lacturat Topic
Or. V.K. Chopra
Shri V.D. Osnda
Or* P«K. Iyengar
Dr. A.K. 0«in
Or* D«R» Nadfcarnl
Dr. K.R^P.n. Rao
Cr. I/.C. Sahnl
Or* A, Sequeira
Dr. P.. 5ubr*aanian
5r-?i Y.D.
Cr. i<f' Rao
"Approach to Absoluts Zero"
"Neutron Radiography"
" F a c i l i t i e s at BARC and thaRecant £xpari»anta"
"Nuclaat Structura froa NuelaarRaactiona"
"Nuelaar Fiaaion*
"Hoatbauar Spactroaaapy"
"Oiract Cnargy Convaralen*
"Ntutron Seattaring fo* StudyingCondanaad Syataaa*
•Soac Aapaeta of tha Uncer ta in tyPrincipla"
"Neutron Radiography for Mon-dsatruct iva Taatlng"
•Kas8b»u«r £Tract Spactroseopy*A Non-daatructlva Tasting TealIn Staal Iaduatry"
To tha National Scianca Talant SaarehScholars.
- do -
- do -
- da -
- da -
- do -
- do -
- da -
- do -
BARC Couraa on "Advanea* in Non»daatruetiva Tasting Tachnlquaa*
- do -
CD
-159-
LECTURES Ht tO UNOiH THE AUSPICES Of THEPHYSICS COLLOUUIUn DURING 1974
Speaker Title of Lecture Oat*
Dr. 6. RajasekharanT.I.F.R.
Or. Martin BlumoBrookhaven NationalLab., Upton, N.Y.and Stony Brook, N.V.U.S.A.
Or. U.K. Chopra
Or. Frank PlasilOak Ridge NationalLab., U.S.A.
Prof. K. BethgeUniw. of HeidelbergW, Germany.
Prof. C.K. flajundarT.I.f.R.
Or. L.C.W. HobbieHead, Neutron Bee*Research UnitRuthorford HighCnaryy Lab., U.K.
Or. A.K* Oain
Prof. W.t. UallacaUniw. of PittsburghU.S.A.
Prof. B. BanerjeaT.I.F.R.
Or. C. Nanohar
Or. fiatigarl
Or. K.G. PrasaOT.I.F.R.
"The Noutrel Currant - a nsw elaaa of January BWeak In tar act ions'*
•Trieritical Point* and Staggarad January 17nagnatic fialda"
"Resistivity Cleaourements on Nb- January 22alloys"
"Hsavy Ion Flaaion and Fusion January 28Reactions"
"Haavy Ion Physic*" February B
"Some rsaulta on Iaing nodal" February 12
•The SRCo Neutron Bean Research February 13Programme"
"Study of Cluster Structure in February 19Light Nuclei"
"Influence of Crystal Fielda on February 21the Ciectrical and Magnetic Pro-perties of Hata Earth Alloya"
"Fast Rotating Nuclei" Karen 5
"Effect of Three-Body Interaction March 19in Hyperfine Fields in Alloya"
"A 2 (IV Tandem Accelerator" torch 26
"Radiation Damage Studies and April 2Location of Inpuritieti .>.• theChannelling
Sftri A.R. Banghar "From Seismcyr«« to Source"
-160-
5hri S.H. KaeturiT.I.F.R.
Prof.I IT
Geabhir
of tha lecture
"Pulaad NNR -Applications in Biology"
"Some of the Recant Trends in theNuclear Structure Theory"
Or. Shankar Mukherjae "Dauteron Stripping Reaoticn neasS.H.U. Coulomb Barrier"
Or. tfijay Mondka8 . I .T .S . , Pi lani .
"Flva-yaar Intagrated Progra«a)»with Practice School1*
Or. Gena 0. Sprouea "One-electron ato«a of F"State Univ. of Ne* forkat Stony Brook,. U.S.*.
Or. K.R. Rao
Shri R.I/. Mandedkai-
Smt. A.S. ParanJpS
"Slow Neutron Physics in U.S.S.R."
"Irradiation irrecta in Nolybdenuaand Rheniuai"
"Electro-Optic Cffecta in LiquidCrystals"
Shri O.K. Srlvaatfava "A Conalatant Picture of tha
Shri R.K. Chowdhury
Shri P.P. Chandra
JIT Kanpur.
Optical Modal in Nuclear Physios"
"Studies or LCP Caiasion in Fiawlon"
"An Introduction to PhotovoltaicCalls»
"Study of Reactor Materials byPositron Annihilation Technique"
Shri C.P. Copalaraaan "Sequential Iapact Multiple Ioni-Technio*i Physics On. sation"
Shri V.C. Rakheeha
Or. K.t.C. LoebnarTech. UniversityMunich.
Shri S. Kailaa
Or. W.C. KoablarSolid Stata Division0.R.N.I., U.S.A.
Or. W.C.. KoablarSolid State Oiviaion0.R.H.I... U.S.A.
Shri . 9«ns«-l
"Spin Oensity Investigation inHagnetica"
"Nuclear Soactroacopy in tha secondwall of **%•
"(p,n) Raactiona and NuclearStructure"
"Current Nautron Physics Reeaarehat tha Oak Ridge National Lab."
"Selected Topioa on Magnetic
"dynamics of nixed Crystals"
Data
April 16
April 23
July 2
3uly 23
August 20
August 13
August If
August 27
September 3
S«pta«tar 3
Ssptsabsc 10
September 13
Sapteobar 24
October a
Novsabsr 6
Novsaber 8
Oecaaber 3
Decsabor 4
11
-161-
PUBLICATIO.'JS
I. PAPERS PUBLISHED
1. Oistorted Ulaue Investigation of alpha-cluster Knock-out In Li,
A.K. Dain and N.Sarma, Nuclear Physics A 23S, 145 (1974).
29 322. Si(«,n) S reaction from 2.15 to 5.25 P!eV bombarding energy
f1?. Belakriahnan, fl.K. Plants, A.S. Oivatie and S. Kailas
(To be published in PhyB.Rev.)
3. A rule for the g.s. spin of light doubly odd nuclei,
5.K. Gupta (To be published in Phys. Rev.)
4. Pressure-Yield Characteristics of R-f ion sources,
S.N. Pllsra and S.K. Gupta, Nuclr. Instr. Methods 122(1974) 303.
5. Model Dependence of the (Jl (nn) Reaction, S.K. Jain,
Nuclear Phys. A 221 (1974) 421.
6. A New Technique for Fluorescence X-ray Counting, U.R. Raikar,
R.U. Ganatra and fladan Lai, International Journal or Nuclaar
Medicins and Biology, i, 215 (1974).
7. Super fluid Properties of Excited Nuolai arising from a -fore*
Raaidual Interaction, l>,G. Clorstto and S.K. Kataria, tattara
AL NUOVU CIO£NT0 g, 190 (Feb. 1974).
8. Production of Nuclei in th<* Reaction* with Kr and Xe Ions ~ Vo.
Ts. Oganeayan, Yu. C. Penionzkavlch, Nguyen Tae Ann, O.n. Nadkarni,
K.A. GavriJov, Kin 01 En and n. uaaonua, Soviet Journal of Nuclaar
Phyeica 2£, 377 (April 1974).
9. Energy Oepandsncv of the Croaa-sectiona for fisaion and nuclaon232 74
transfer in interaction of Th with acoalarated Ga ions,
Yu. T*. Oganeeyan, U ,fl. Nadkarni, Yu. E. Penionzkewich, B.I.
Pustylnik and Nguyun Tao Ann, Soviet Journal of Nuclear Phyeloa
V9_, 244 (Ssptaabar 1974).
-162-
10. Spin Relaxation in Olaordered Niekal l ine rarr i tea using fosabauer
Ef fect , S.C. Ehargava and P»K. lyangar, 3. da Phyaique 3& (1974) .
1 1 . Hyperfine Interactions of Iron in Tarnary Alloya with 86. Typa
Structure, S.C. Shargava and P.K. Iyanger, Prauena g, 126 (1974)*
12. l a t t i c e Dynamic* of BaryXllum, B.A. Daeannaoharya, P.K. lyangar,
H.V. Nandedker, K.8. Rao, A.P. Hoy and C.L. Thapar, Praaana 2,,
179 (1974).
13. 2 x 2 Cyclic natricaa and Lucaa Polynomial*, I .V .V. Raghavachar-
yulu. The matrix and Tanaor Quarterly 25, 59 (1974).
14. PolynoMlal Algebra*, I .V .V . Raghavacharyulu, 3. Hath. Phye.
125$ (1974) .
15. On the Generating Relation* of Spi.t and Pasafleld Algebras,
I .V .V. Ragnavacharyulu, Thsor. Hath. Phya. (Acadeny of Solaneee
U.S.S.R.) 22t 305 (1974).
16* Dynamic* of Liquid Aansonla f ro * Cold Neutron Scattering, C.L. Thapar,
B.A. Oaaannacharya and P.S. Goyal, Praaana 2j 148 (1974) .
17. Non-sphorical ffagnetic Moment i n flnAlGe, S.K. Paranjpa, S.f l . T«n-
dulkar, L» Itadhaw Rao and N.S. Satya Nurthy, Pranana 3,, 355, 1974.
16. On the application of group theory to apin waves in coll inear Mag-
netic structure*, V.C. Sahni and C. V»nkatara«an, Adv. in Phya.
23, 547 (1974).
I I . BOOKS PUBLISHED
1 . Oynataice of Perfect Crystaia, 6 . Wsnkataraman, i-.A. Taidkaeip and
U.C. Sahni ( I1 . I .T . Prase, Cambridge, Ptaaa).
-163-
II. PAPERS PRESENTED AT CONFERENCES
36•1. MigheT isospin states in Ar though alpha particle Capture
Resonances, D.R. Chakraborty, PI.A. Eswaran, H.H. Oza and
M.L.
2. Proton Knock-out Reactions and Cluster Structure in Li Isotope*,
fl.K. Jain end A.K. 3ain, International Conference on Few Body
Problems in Nuclear end Particle Physics, Quebec. Aug. 1974.
1 g 22• 3. f(«>i ,n) Ne Reaction in the energy range 2.6 to 5.1 fleVj
PI. Salakrishnan, S. Kailas, S.S. Kerekatte and fl.K. flehta.
•4, A method for determining target thickness for thin targets
evaporated on thick'backing utilizing back-scattering of alpha
particles, !•). Bslakrishnan, S, Kailas, S.S. Kerekatte and
M.K. flehta.
29 32•5. Si(ttf,n) S reaction near threshold, M.Balakrishnan,
S. Kailas, S.S. Kerekatte and fi.K. Clehta.
*6. CJn the fundamental representation of SU (3) group, S.K.Gupta
and I.V.V. Raghauacharyuiu.
55 55*V. Study of the reaction On (p,n) Fe from Ep = 1.35 MeV to
5.4 Wev, S. Kailas, V.P. Viyogi, S. Saini, S.K. Gupta,
^.K. Gc.nc.jly, Pl.K. rtehta, A. Bannerjea, b.b. Karekatte.
*8» Nuclear Structure study of °V by the bUTi lp,nT } V Reaction,
ii.K. Gupta, S. Saini, L.V. Jamjoshi and fl.K. Hehta.
*9. Automatic Scanning of Excitation function, P.3. Gh«ler«o,
N.Y. Uazs, S.K. Gupta and C.U.K. Baba.
•10. Installation of Z/H Analyser on Trombay l/an-de-Graaff Accel«rator
S.N. flisra, C.V. Fernandes, and S.K. Gupta.
•11. Resonance spectroscapy of Si nucleus in the excitation energy
range 14.276 fteV to 15.022 ftel/. L.V. Namjoshi, S.K.Gupta and
("!.K. Wahta.
-164-
•12. Spectre of doubly odd-odd nuclei, S. Saini end S.K, Gupta.
*13. Ga+ Implanted p-n-junctions in silicon, A.G.ltleghj
P.K. Bhattacharya and N« Sarms.
*14. An Insulated core Tran&former Poiuer Supply for Ion-Implantation
M.S. Shatia, N. Sarma and C. Paramaaivan.
•15, Index of refraction changas in glees due to ion implantation
P.K. ahattacharya, N. Sarma and A.G. k/agh.
Alpha Particls Trajectory Calculations in Spontaneous Ternary252
fission of Cf and Studies of Scii
fl.K. Choudhury and V.S. Ramamurthy.
212fission of Cf and Studies of Sciaaion Point Configurations,
# 1*. Alpha Particle Trajectory Calculations in Spontanaou* Quarternary
Fission of 2 5 2Cf, i».K. Kataria.
•18. Three Dimensional Correlations of Fragment Hase, Fragment tnargy
and Long Range Alpha Particle Energy in the Fission of U-235 by
'i hernia 1 Neutrons, O.I1). Nadkarni, H .K. Choucihury, S.R.b. liurthy,
P.K. Hama Rao and S.S. Kapoor,
*19. AitMonium Ion Librationa in Cu f ^ ^ ^ J i ^ ^ O Hlxsd
Cryetala, «.L. Sansal, W.C. Sahni and A.P. Roy.
20. Spin Rslaxatlon in Oisordsred Nickel 2inc Ferritss using
noasbauar Effact, S.C. Bhargava and P.K. Iyangsr, Int. Conf.
on the Applications of tha Wosabauar Effaot, Sandor (FrancaJ,
(*» 974 ) •
•21. Raflsctivlty of flonocrystals in rtultiplane Caosiatry, P.P.Chandra
and 8.A. Oasannacharya.
•22. Ra-oriantationol notion of Aa*oniu« Ion In U x a d Salt of
(NH 4) 2S0 4 and I^SO^, P.s. Go y.i t p.p. Chandra, K.R. ftao and
C.L. Thapat.
Aepharical ftc^nt O.n.ity in BnAICa, S.K. Paranjpa, S.R. T#nd«lkar,
L. Madhav Rao and N.S. Satya Nurthy.
-165-
1*> &uri-»phei'ical Magnetic Moaiant in flnAlGa ( *b* t r *ct only) ,
S.K» P.ranjpe, 3-ft. T*ndulk«r, L. Kadhav H«o «nd «*S. S*tya fluvthy,
20th Ann. Conf. on Magnet!»• and ftagnetlc f latariala, San
Cal i f , (1974),
•2S. On the Cottec :r,:a» of Slatsr 'a Notation, I-U='J.
'•i6. Scattering Tensor* for Rs*onanca Raaan Scatti.uir.y in
Hexuoontil Lattice Syatsma, I.U.W. Ragha»«chrttyuiu.
''•'}1* Ptosobauor Spectroucopy Study of Short-Ranyt> i\«-.|!io<.ic Ordfering in
Co-Ga (' To) Intariaetaliio CoMpounda, K.K.t-.H, Hoc, aad f*K.lycngaro
ftoiocula; Oynanics of 4-nHiaxyloxyh»niylidan*-4v
5.X. Sinhar K. Usha Denii , G. V«nkatara*an, 8«A
AoS. Paronjpe and P>^> Parwathanathan, Uth Intt. Conf, an Liquid
, Stomthplci, Swadan (1974).
Llbration WorJya of Uatar ftolaeulaa in Singia Ctyutai af 9aS0.4H,0,
C.L. Th«pesrs T. Siriniwaaan and P«K. Iyangat.
Qistoftod Singia Ctyatala aa Nautron nonoshto«attira^ C.L. Thapar,
A.S, Oaahpanda and P.K>.-.-^MVJI
»MucX«ar i^ysicu & Solid Stata Phyaica Syapoaiua ( 0 « ) So«bay(t974^
-166-
THCSIS SOBWITTCO TO
1. Study of flagnatlo Propsrtiaa of Farritaa and Alloys using the
HoaahauM Cffact, S.C. Shargava, (Ph.O.), Unlwaraity of la«b«;.
- 1 6 7 -
NUCLEAR PtyVfrlt^ 01,VISI0S STAFf
Or. P»K. Iyongar O i rac to r , Phyaien Group
Or. U.K. Muhta Haad, Mucisar Pttyaica OlvlaXon
A. VAW QE GHAAff LABORATORY
Haad t Ot . H.K.
Nui
1 .2.3 .4 .5»6 .7*6 .
slear
Dr .Or .ShriShriShri5hriSmt.Shri
Reactiona-I
11.K. MahtaS.K. Uuptan. 6alakriehnanS.S. KerskattaS. KailasS.S. SainiLa lit ts PiamjoshiC.U. fernandu*
(NST Scholar}
9. Or. rt.G. Batigeri10. Shri Mohammed la/nall-11 . Shri ft.P. Anand
I I . Nuclear Reactiona-II
1. Or. M.A. Eswaran2. Shri N.L. Ragoowanai3. Shri O.H. Chakraboraty4. Shri H.H. Uza
III . Nuclear Theory
1 . Or. N. Sarma• 2 . 05. B.K. 3ain
3 . Dr. A.K. -lain
IV. Nuclear Spectroacopy
1. Or. C.V.K* Baba2. Shri P .3 . Bhaleiao3 . Shr i V .S . AsbskarA. Shr i H.V. Vaza5. Shri H.5. Patwarrthan
• On COL to Univ. of nanitoba, Canada.
-168-
V. Van da Graaff Halntananca t
1 .2 .3 .A.C=.• s
6 .7 .
ShriShrlShriShriShriShii:int i
V . A .
n.s.S.M.o .s .5 .G .P.ft.
HttttangcdiBhatiaWisraBiahtShukla^undar Raoaliratt
a. Shri i>.0. riandkB9. Shri R.*-'. KulkarniId ihri II.t. Oactor
^^ • Jootops Separator
?. Shri t.A. Hattangadi2 . Shr i T .R . Bhathena3 . Shri K .L . Pate l4 . Shr i £• Shallow
VII. Ion Implantation
1 .2 .3 .4 .5.6 .
Ta_<
* «2 .3 .4 .5 .
O r .O r .Or.ShriShriShri
O r .O r .ShriShriShri
f>. SarmaO . K .P . K .
M.S.A.G.n.j.
So adShattacharya
> Bhetie> Jitegh' kansart
Accelerator Projact
W . K .
T.P.n.s.
RahtaBatigerl^oniOavidBhatiaati»
6- Shri C U . Rayatappan
e. nss^H fHirsics SECTIOW
Haad i Or. S.S. Kapoar
I. flaaton Physics
1. Or. R. Ramanna2. Or. S.S. Kapoor3. Dr. D.n. Nadkarni4. Or. V.S. Ramamurthy5. Shrl N.N. Ajltanand6. Shri S.K. Katarla7. Shri fi.K. Choi<dharyB. Shrl H. Prakaah
9. Shci P.N. Rama Rao1Oa Shrl nadan Lai11. Shri S.R.S. Wurthy
-44 . Shri B.H. 8a l ia l12. Shri S.L. Raote13. Shri K>N. Iyengar
C. SOLID STATE PHYSICS SECTIOM
Head i Or. N.S. Satya Burthy
I. Neutron Diffraction & Scattering
1. Or. N-S. Satya Hurthy2. Or. L. Hadhau Rao3. Qr.(Smt.) R.3. Begun4. Shri I/.C Rakhecha5. Shri S.K. Paranjpe6. Smt. 3. Chakravarthy?. Shri S.R. Tendulkar (Bowbay Univ. Studen'r:•',
3. Or. P.K. Iyengar9. Or. B .A . Oasannacharya
10. Dr. K.R- Rao1-1. Shri C.L. Thaper12. Shri P.S. Goyal13. Shri P.P. Chandra
• 14. Shri A.H. Wenkatesh15. Shri P.K. Dayaniclhi
16. Shri P.H. Uijayaraghavan17. Shri C.S. Somanethan18. Shri B.S. Srinivaaan19. Shri M.H.L.N. .Murthy20. Shri * .S . Oeahpanda2 1 . Shri T. Srintuaaan
I I . Theoretical Group
1 . Or. R . Subramaninn2 . Or. I .V .V. Raighavacharyuiu3 . Shri K.V. Bhagvat* . Shr i S. 3yothi5 . Shr i S. Lakshmi n ataaiwhan
6 . Or. V.C. Sehni7. Shri P. Chaddah
I I I * Light. Seat-taring
1 . Dr . (S« t . ) K. Uaha Dani*2 . Shri P-S. Pat«- +»*anathan3 . SMt. A^S.
•On Loan rro* RRC.
-170-
JV,
4* Or. *.P. Hoy5. Shri 1«L. Banaal6. Shri T.R. Rao
Stud lea
(8oHb«y Univ.
1 . Or. p.K. lyengar2 . Dr, K.R .P.H. Raoj . Stir i S.C. Shargava
V. Cgypfienice
1 . Or. N . 3 . batya Hurt fly24 Or . U.K. Chopra3,. Shci G. Ufiarmadural
0. bUPPURTlWG
I. Neutron Detectors
t. Shri Y.U. Uande2. Shri H.L. Jain3 . Shri R.S. Udyeuar4. Shri G.V. Shenoy5. Shri S.R. Chinchr
snenoyChinchnikar
6. Shri A.P. Bagool
II. Electronics Oeeion & OaveJ.ciownt
i , Sr,v i V. Singh2. inn V.I1. Shah3. Shri R.S. Kotharo4. Shri J.N. 3aohiI-.. Snri U.U. Gaonkar5. Si-.ri N.O. Kalikar
III. Workshop
. . Shri J.N. Soni2 . shri K.R. Ohali3 . Shri V . B . Oixit4 . Shri J.S. Chawla5 . Shri S.R. Sauant6. Shri P. Narayanan
E . AD111NISTSAT1ME STAfF
1 . Smt. Vijeya R*win<tr«niith2. Shri A.3. Kulkarni3. Shri R- Sadaalvan PiXlai* , S*t. Pr»« Krishnan5, Shri B.R. Gauhar6. KUM. V.R. Chitaia
