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DEPARTMENT OF PHYSICS

Department of Physics > HEP Home > Experiments > ATLAS > SCT Operations > Hardware

SCT Endcap C

High Precision Tracking at the LHC

The Liverpool ATLAS group was involved in the construction, testing, installation and commisioning of the SCT Endcap C.

Module Production

The organisation of the international programme for the production of forward modules across 15 institutes was led by Liverpool. This followed Liverpool's central role in designing the wedge shaped sensors for the forward region and defining the forward module design.

The group's role in the production of the SCT Forward Modules was two-fold. Modules produced by outside institutes were acceptance tested before they were mounted onto discs. This was done in parallel with the production and full characterisation of modules bonded in-house.

Three types of endcap modules

The Liverpool group had responsibility for wire-bonding 300 double-sided modules (each with 2310 bonds per side) following a thorough initial visual inspection. The modules were then thermally cycled and their metrology checked against initial measurements using the SmartScope. The modules were then characterised, with measurements being performed of I/V, full ASIC functionality, timing and noise. The electronics test system, which exercised the hybrids through the opto-readout, but allowed use of the electrical connections, was designed by Liverpool. A yield of 94% was achieved for the modules bonded at Liverpool.

Assembly and testing at Liverpool

The design of the tooling to enable modules to be mounted onto discs was finalised following prototyping for the 3 different types of module. The tooling was then manufactured and commissioned by Liverpool.

The discs were prepared with cooling pipes, precision mounting blocks, electrical services and optical fibres at RAL. On arrival in Liverpool, a number of acceptance tests were performed, including a visual inspection, leak tests, tests of the electrical connections, tests of the optical fibre connections and metrology of the mounting pins using the Coordinate Measuring Machine.

(Left) Disk 6 in the assembly jig. (Right) A close up of a completed disc on the endcap

Each disc was mounted in the assembly jig and the modules were then assembled. A total of 988 modules were successfully mounted onto 9 discs with no losses.

The test box to allow the discs to be cooled and electronically tested in the large environmental chamber, with thermal measurements taken using the thermal camera, was designed, manufactured and commissioned in-house, including the design and manufacture of the heat exchangers and the installation of all the necessary pipe work for the evaporative cooling system. The installation of cables, optical fibres, power supplies, slow controls and SCTRODDAQ completed the infrastructure.

Each complete disc was transported to, and then mounted in, the test box in the environmental chamber. The evaporative cooling plant supplied coolant at -25°C and the functionality of each module was checked. The characterisation of the full disc was then performed and thermal images taken and analysed to confirm the cooling performance.

Noise measured on the four types of endcap module

Noise distributions for all the 988 mounted modules. The different colours indicate the four different module types. Each disc was mounted in the assembly jig and the modules were then assembled. A total of 988 modules were successfully mounted onto 9 discs with no losses. Each complete disc was transported to, and then mounted in, the test box in the environmental chamber. The evaporative cooling plant supplied coolant at -25°C and the functionality of each module was checked. The characterisation of the full disc was then performed and thermal images taken and analysed to confirm the cooling performance.

Please see the following link for detailed test results

Mounting the Discs into the Support Cylinder

The mounting of the discs into the support cylinder was undertaken in collaboration with Glasgow, Lancaster, Manchester, RAL and Sheffield. Many engineering tasks were performed in assembling the cylinder, with modifications to the thermal feed-through, the attachment of various mounting clips for the services etc. being necessary followed by extensive mounting and testing of all services (cooling, low-mass electrical connections, optical fibres).

A view of the endcap after the insertion of the last disc.
A "warm test" was developed by Liverpool to check the connectivity of the low mass tapes and optical fibres. This allowed the connections through to the modules to be checked using SCTRODDAQ without running the evaporative cooling. During the assembly, EndCap-C was placed in the environmental chamber of the LSDC and electronic tests were performed at -10°C, while keeping the dew-point at -30°C.

Transportation to CERN

Endcap C arriving at CERN

The original transport frame for the end-cap was designed at NIKHEF. Major changes to the design were made necessitating a trial run to assess the proposed procedure for loading and unloading and to evaluate the effectiveness of the design in reducing shocks to EndCap-C. The results demonstrated the feasibility of the transport of EndCap-C to CERN which was completed successfully in February 2006.

Endcap-C safely delivered to CERN and up-packed

Installation into ATLAS

On 18th June 2007 Endcap C was moved from the surface building and lowered into the ATLAS experiment. The next day it was installed into its final position inside the calorimeter of ATLAS.

Endcap C arriving in ATLAS
Endcap-C in it's final position inside ATLAS

The Liverpool group were heavy involved with the fibre/power cable connections and testing and are currently working on calibrating and commissioning the detector

- SCT Endcap C Disk 6 -

Useful SCT Links:

SCT Web Page

Endcap-C Test Results

Endcap-A Test Results

Barrel Test Results

SCT Commissioning