MS Supplies Technical Description Template

December 2020

CERN EDMS: 2442090

Group Code: EP-CMX

MS-4640/EP

The CMS Outer Tracker Phase II upgrade

Market Survey

Technical Description

Supply of Aluminium-Carbon Fibre Metal Matrix Composite

Material and Parts for the CMS Outer Tracker

Abstract

This Technical Description concerns the supply of a large number (up to

about 30,000) of machined Aluminium-Carbon Fibre Metal Matrix

Composite Parts, requiring production of about 50,000 cm3 of raw Al-CF

material, for the Outer Tracker of CERN’s CMS experiment. This Market

Survey will be followed by one or several Invitation(s) to Tender planned to

be issued in 2021.

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Table of Contents

1. INTRODUCTION ..................................................................................................................... 1 1.1 Introduction to CERN .................................................................................................................. 1 1.2 Introduction to the CMS Experiment ............................................................................................ 1 2. SCOPE OF THE SUPPLY ........................................................................................................ 4 2.1 General ........................................................................................................................................ 4 2.2 Deliverables and Activities .......................................................................................................... 5 3. REQUIREMENTS .................................................................................................................... 5 3.1 Technical Requirements ............................................................................................................... 5 3.1.1 Raw Material ............................................................................................................................... 5 3.1.2 Finished Parts ............................................................................................................................. 5 3.1.3 Parts for Modules ........................................................................................................................ 6 3.1.4 Parts for Support Structures ......................................................................................................... 6 3.2 Norms and Standards ................................................................................................................... 7 4. PERFORMANCE OF THE CONTRACT ................................................................................ 7 4.1 Delivery Schedule........................................................................................................................ 7 4.2 Acceptance Tests ......................................................................................................................... 7 5. CONTACT PERSONS AT CERN ............................................................................................ 8 6. LIST OF ANNEXES .................................................................................................................. 8 6.1 List of Drawings .......................................................................................................................... 8

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1. INTRODUCTION

1.1 Introduction to CERN

CERN, the European Organization for Nuclear Research, is an intergovernmental organization with

over 20 Member States1. Its seat is in Geneva but its premises are located on both sides of the French-

Swiss border (https://maps.web.cern.ch).

CERN’s mission is to enable international collaboration in the field of high-energy particle physics

research and to this end it designs, builds and operates particle accelerators and the associated

experimental areas. At present, more than 10 000 scientific users from research institutes all over the

world are using CERN’s installations for their experiments. Further information is available on the

CERN website: http://cern.ch.

The accelerator complex at CERN is a succession of machines with increasingly higher energies.

Each machine injects the beam into the next one, which takes over to bring the beam to an even higher

energy, and so on. The flagship of this complex is the Large Hadron Collider (LHC) as presented on

the CERN website: http://cern.ch. The LHC collides proton beams at a center of mass energy of 1300

TeV in the center of four detectors that are arranged around its 27 km long circumference.

1.2 Introduction to the CMS Experiment

The Compact Muon Solenoid, or CMS (http://cms.cern.ch), is one of the particle physics experiments

at the Large Hadron Collider (LHC) at CERN. The CMS detector is designed to study particles

produced in high-energy proton-proton and heavy ion collisions to seek answers to fundamental

questions such as: “understanding why the world is the way it is, why some particles weigh more than

others and what constitutes the dark matter in the Universe”. The CMS detector is located 100 m

underground at the French village of Cessy near Geneva. The experiment is in operation and the data

now being collected by CMS is distributed to institutes around the world to be analysed. The CMS

collaboration involves more than 4300 particle physicists, engineers, technicians, students and

support staff from 179 universities and institutes in 41 countries.

The current LHC program will end in 2024 with Run 3. After that the LHC will be upgraded to

operate at significantly higher luminosity. The upgraded machine will be called high-luminosity LHC

or HL-LHC. It will begin operation in 2027. The higher luminosity of the HL-LHC means that many

more particles will impinge on the CMS detector than what its detector systems were designed to

handle. Therefore, an extensive upgrade of the CMS detector will take place in the coming years.

One of the detector systems which will be entirely replaced is the tracker which measures the

trajectories of charged particles from the proton-proton collisions. The current strip and pixel trackers

will be replaced by new Outer and Inner Tracker detectors (see Figure 1).

The Outer Tracker will consist of about 13,200 modules, each built up of two silicon sensors separated

by mechanical spacers. The design of a representative example of such a module is shown in Figure

2. The yellow rectangles in the figures are the silicon sensors. The three orange flex circuits

accommodate the readout electronics and power supply for the module. The two sensors are separated

by two long main bridges on either side and one short stump bridge in the center of the module. These

are drawn in grey in the figures. These bridges are part of the Supply described in this Market Survey.

It is critical for the function of the modules that the two sensors are precisely coplanar. To keep the

1 http://home.web.cern.ch/about/member-states

https://maps.web.cern.ch/

http://cern.ch/

http://cern.ch/

http://home.web.cern.ch/about/member-states

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dark current in the silicon sensors low and limit reverse annealing of radiation damage, the entire

detector will be operated at -30C. Therefore, the detector has to be able to withstand repeated

temperature cycles between room temperature and -30C.

Figure 1: Perspective view of the new Outer and Inner Trackers for CMS. The small

rectangles that populate the disks at the ends and the concentric cylinders at the center of the

structure are the modules of the Outer Tracker. The cylinders are referred to as the barrel

part of the tracker.

Figure 2: Assembled view (left) and exploded view (right) of 2S 1.8mm Module.

The designs of the bridges are driven by the requirement that they should have as little mass as

possible, yet provide sufficient heat conduction to keep the sensors cool during operation. Their

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coefficient of thermal expansion (CTE) should be well matched to that of silicon to minimize

mechanical stresses in the modules when they are cooled down.

These modules are mounted on support structures that also serve to cool the sensors with a two-phase

CO2 cooling system. To achieve effective cooling, the mechanical structure of the modules and the

supports have to establish a good thermal contact between the sensors and the cooling medium.

Some of the modules in the barrel part of the tracker are mounted on carbon fibre cooling plates that

are arranged in a ring as shown in Figure 3. The cooling plates are attached to cooling pipes using

cooling adapters of triangular cross sections with various angles. The CTE of these cooling adapters

also has to be matched to that of the modules to avoid warping when the tracker is cooled down.

Figure 3: Ring support structure for barrel modules at smaller radii.

A different part of the barrel support structure is shown in Figure 4. The special inserts are also part

of the Supply. They are large enough that their CTE must be matched to that of the modules.

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Figure 4: Ladder support structure for barrel modules at larger radii. The left panel is a blow

up of the support structure for module #1.

2. SCOPE OF THE SUPPLY

2.1 General

CERN intends to place one or several contracts for the supply of a large number (about 30,000) of

machined Aluminium-Carbon Fibre Metal Matrix Composite (hereafter referred to as Al-CF) parts

for the CMS Outer Tracker, requiring the production of about 50,000 cm3 of Al-CF raw material in

the form of blocks. The Al-CF material block production and the part machining (hereinafter referred

to, in whole or in part, as the “Supply”), are defined in this Technical Description, including its

annexes and in accordance with the criteria defined in the Qualification Questionnaire.

These parts will be used in the Outer Tracker of the CMS experiment at CERN. These modules are

mounted on support structures that also serve to cool the sensors with a two-phase CO2 cooling

system. To achieve effective cooling the mechanical structure of the modules and the supports have

to establish a good thermal contact between the sensors and the cooling medium. To keep the dark

current in the silicon sensors low and limit reverse annealing of radiation damage, the entire detector

will be operated at -30C. Therefore, the detector has to be able to withstand repeated temperature

cycles between room temperature and -30C.

The Supply will be used for the mechanical support of the sensors and read out electronics hybrids in

the modules of the Outer Tracker and for mounting the modules on the support structures.

One or several Invitation(s) to Tender will be issued following this Market Survey. CERN reserves

the right to split the contract among several contractors. Only firms qualified and selected by CERN

after analysis of their reply to this Market Survey and successful completion of the qualification

procedure defined in this document, will be included in the forthcoming Invitation(s) to Tender. The

supply shall originate from CERN Member States or CMS2 Member States.

2 List of CMS Member States: Austria, Belgium, Brazil, Bulgaria, China, Colombia, Croatia, Cyprus, Czech Republic, Egypt, Estonia,

Finland, France, Germany, Greece, Hungary, India, Iran, Ireland, Italy, South Korea, Lithuania, Malaysia, Mexico, New Zealand, Pakistan, Poland, Portugal, Russia, Serbia, Spain, Switzerland, Taiwan, Thailand, Turkey, United Kingdom, US

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2.2 Deliverables and Activities

The Supply shall include the following deliverables and activities:

• Production of raw Al-CF material;

• Machining high-precision parts from the raw Al-CF material;

• Supply of extra raw Al-CF material without subsequent machining;

• Packing of the Supply;

• Quality assurance and the related documentation;

• Shipping to CERN.

3. REQUIREMENTS

3.1 Technical Requirements

3.1.1 Raw Material

For the CMS Outer Tracker, Al-CF is the best material to satisfy the requirements of high thermal

conductivity and low coefficient of thermal expansion (CTE). The material of the Supply must be

equivalent to Al MetGraf 4, manufactured by Parker Hannifin Corporation.

In particular, the material must have the following properties:

• High thermal conductivity (at least 220 W/mK in the xy plane and 120 W/mK in z direction);

• Low CTE to match silicon (at most 4 ppm in the xy plane and 24 ppm in the z direction);

• Low mass density (at most 2.6 g/cm3);

• Young’s modulus > 95 GPa;

• Flexural Strength >120 MPa;

• Homogeneous CF density throughout the volume, defined as < 20% variation in the CF fraction

in volumes larger than 1 mm3.

The xy plane is the plane in which the carbon fibres are oriented and the z direction is transverse to

the xy plane. To reach the required properties the material shall consist of chopped carbon-fibres

randomly oriented in the xy-plane. The properties in the z direction are dominated by the properties

of aluminium.

In addition to the Supply of parts, CERN may order raw material in the form of blocks. The amount

of raw material will probably not exceed 15-20% of the material required for the parts specified in

section 3.1.3.

3.1.2 Finished Parts

The design of the parts will be communicated to the contractor in the form of technical drawings that

will be similar to the drawings that are shown in this Market Survey. Final drawings will be supplied

with the Invitation to Tender.

One is free to propose a suitable machining method, conventional or non-conventional, or any

combination. A detailed account of the proposed strategy, shall be documented in the reply to this

Market Survey. It is important that the dimensional tolerances and high-quality of the surfaces and

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edges are maintained as specified in the example drawings and that the composite material is oriented

as specified.

Preliminary specifications are given in the drawings in the addendum of this Market Survey. Final

specifications will be supplied with the Invitation to Tender.

The Al-CF metal matrix composite is fragile and brittle. It is inherently difficult to work with.

Therefore, only firms that have demonstrated prior experience in manufacturing parts from this

material will qualify for the subsequent Invitation(s) to Tender.

3.1.3 Parts for Modules

The CMS Outer Tracker comprises about 7184 detector modules with 1.8 mm spacing of the two

sensors and about 424 modules with 4 mm spacing of the two sensors. Each module requires two

main bridges and one or two stump bridges in Al-CF. Table 1 gives the total number of parts including

15% spares. CERN may place a contract for the full quantity or for a partial quantity. Preliminary

design drawings of these parts can be found in the appendix.

Table 1: Module parts.

Part Number per Module Estimated Total Number

2S 1.8mm Main Bridge 2 16524

2S 4mm Main Bridge 2 976

2S 1.8mm Stump Bridge 1 8262

2S 4mm Stump Bridge 1 976

3.1.4 Parts for Support Structures

The detector modules are supported and cooled by ring and ladder structures. Parts made of Al-CF

act as supports and thermal interfaces for the modules.

The CMS Outer Tracker comprises about 72 ring structures plus about 18 spare rings. The Al-CF

parts needed for these rings are triangular in shape. They are of seven types, each with a specific

angle.

Table 2 gives the parts required, their numbers including parts for spare rings plus 10% spare parts,

for a total of about 2640 parts. Preliminary design drawings of these parts can be found in the

appendix.

Table 2: Ring structure parts.

Part Estimated Total Number

Cooling Adaptor 40 deg Pipe 2.5mm 229







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In the ladder structures the Al-CF parts are of two different types. The Outer Tracker comprises about

368 ladders plus about 40 spare ladders. Including 10% spare parts, about 450 of each of the two Al-

CF part types are needed. Preliminary design drawings of these parts can be found in the appendix.

Table 3: Ladder structure parts.

Part Estimated Total Number

Special Insert X plus 450

Special Insert X minus 450

3.2 Norms and Standards

The Supply shall comply with the ISO norms and standards referred to in the technical drawings.

• ISO 14253–1: Geometrical Product Specifications (GPS) – Inspection by measurement of

workpieces and measuring; equipment — Part 1: Decision rules for proving conformance or non-

conformance with specifications;

• ISO 1119:2011: Geometrical Product Specifications (GPS) – Series of conical tapers and taper

angles.

4. PERFORMANCE OF THE CONTRACT

4.1 Delivery Schedule

The Contract is scheduled to be awarded in Q2 or Q3 of 2021, following the Invitation to Tender to

be issued in Q1 of 2021. The final delivery schedule, of about 18 to 24 months, will be stated in the

Invitation to Tender. CERN reserves the right to award several contracts for subsets of the parts listed

in section 3.1.

The deliveries will be structured into two phases: preproduction and production. Preproduction shall

consist of 5% of the contractual quantity for the Supply. The production consists of the remainder of

the full contractual quantity. The start of the production shall be contingent on completion of the

preproduction according to the delivery schedule, and compliance with the final specifications, as

stated in the Invitation to Tender. CERN reserves the right to terminate the entire contract if the

preproduction does not comply with these conditions without any compensation due to the

contractor(s) for such termination.

Production parts shall be delivered in monthly deliveries over a period of about one year following

acceptance of the preproduction parts. Only parts which comply with the technical specifications of

the Invitation to Tender shall be sent to CERN. The final delivery schedule will be defined in the

Invitation to Tender.

4.2 Acceptance Tests

CERN or its collaborating institutes intend to carry out the following acceptance tests in the

framework of the acceptance procedure:

• Inspect the raw material and parts for homogeneity in the carbon fibre content ;

• Verification that the dimensions of the parts conform with specifications ;

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• Verification that the orientation of the fibres conforms with specifications.

5. CONTACT PERSONS AT CERN

All commercial and technical correspondence concerning the Market Survey shall be communicated

to the CERN Procurement officer and in copy to the Technical officer. Any communication by or to

any other person than the CERN Procurement Service shall not be valid and have no effect.

Procurement officer Telephone Email

Mr Charles Carayon IPT/PI Tel: +41 22 766 3328 [email protected]

In case of absence:

Mr Joshua Davison IPT/PI Tel: +41 22 766 4458 [email protected]

Technical officer Telephone Email

Mr Ulrich Heintz EP/UCM Tel: +1 617 959 0687 [email protected]

In case of absence:

Mr Antti Onnela EP/DT Tel: +41 22 767 5758 [email protected]

6. LIST OF ANNEXES

6.1 List of Drawings

Description Drawing number Version

2S 1.8mm Module Main Bridge CMS2T2SM0142 AB

2S 1.8mm Module Main Bridge – Flatness specification CMS2T2SM0106 A

2S 4.0mm Module Main Bridge 0.5 CMS2T2SM0152 --

2S 1.8mm Module Stump Bridge CMS2T2SM0107 AD

2S 4.0mm Module Stump Bridge 0.5 CMS2T2SM0153 --

Cooling Adaptor 40 deg Pipe 2.5mm CMS2TBPS0152 --







Special Insert X plus CMS2TB2S0027 --

Special Insert X minus CMS2TB2S0046 --

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