Mechanical Study of Silicon Strip Detector Modules During Quality Control for the ATLAS Phase-II Detector Upgrade
Following the great achievement by the ATLAS experiment at the Large Hadron Col- lider (LHC) that is the detection of the long-awaited Higgs boson, an upgrade of the LHC is planned, requiring an upgrade of ATLAS. Planned for the High-Luminosity LHC, the ITk (Inner TracKer), an all-silicon charged particle tracker, is the upgrade of the current ATLAS Inner Detector. Testing of the detector modules comprised in the ITk is crucial because the detector will be inaccessible for approximately 10 years following the installation. In this thesis, the focus will be kept on a subset of the ITk detector, namely the ITk Strip detector. To detect premature failure in the 20 000 Strip modules that will be produced, a series of tests will be performed, one of which will be the thermal cycling, where modules are monitored while being thermally cycled to replicate 10 years of operating conditions. These tests will occur in a special enclosure known as a coldbox. The subject of this work is to study the induced mechanical stress in future ITk Strip detector modules due to thermal cycling using Finite Element Analysis. Our first result is that the stress created in the module is mostly due to the vacuum applied to hold the module. Moreover, the maximum stress felt during thermal cycling is highly dependent on the thickness of the vacuum seal used: A thinner seal causes a lower stress. Finally, the stress in the module in our thermal cycling setup is between ∼ 20 MPa and ∼ 100 MPa depend- ing on the selected seal thickness, which is consistent with the stress expected in the final detector design which is approximately 64.8MPa. We can then conclude that the proposed design for the coldbox is a good candidate to perform thermal cycling.
Particles Physics ATLAS Detector Silicon Tracker Finite Element Analysis Mechanical Stress