Development of Pixel Module Assembly Processes for the Phase 2 Upgrade of the ATLAS Detector and Test Beam Measurements with Diamond Pixel Detectors

by Helge Christoph Beck
Doctoral thesis
Date of Examination:2020-02-06
Date of issue:2020-02-25
Advisor:Prof. Dr. Arnulf Quadt
Referee:Prof. Dr. Arnulf Quadt
Referee:PD Dr. Markus Keil
Persistent Address: http://dx.doi.org/10.53846/goediss-7878

 

 

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Abstract

English

One of the most powerful machines to study particle physics is the Large Hadron Collider (LHC). Starting in 2024, it will be upgraded to the High Luminosity-LHC (HL-LHC) to deliver even more data to measure with high precision Standard Model (SM) physics processes, and to maximise the potential to discover new physics. Higher luminosity implies a higher radiation environment, which poses challenges to the detectors of the experiments. To deal with radiation damage, pile up, and needed read-out speed, ATLAS will replace its current tracking detector with the new Inner Tracker (ITk). The innermost part of the ITk will be instrumented with silicon pixel detectors. To ensure a high quality production of these modules, tools and processes for the assembly are developed. In this thesis, prototype tools are investigated for their alignment precision of the involved parts, and prototype modules are built for demonstration purposes. After building the modules, they are mechanically and electrically tested. For this purpose, a test stand is required to perform parallel testing of multiple modules, in a temperature controlled environment. The detailed features of the test stand are presented in this thesis, along with the first validation results. Diamond is investigated as an alternative material to silicon, for developing HL-LHC detector sensors and even more radiation hard applications. Although diamond shows an outstanding radiation hardness, diamond sensors generate weaker signals than silicon ones, when exposed to particles. Furthermore, charge trapping reduces even further the signal in polycrystalline diamond. To overcome these limitations, 3D electrodes in the bulk of the sensor are investigated to reduce the travel distance of the charges. Two pixelated diamond detectors read out with the ATLAS FE-I4 chip are qualified in test beam measurements, one with a planar and one with a 3D electrode geometry. Needed improvements for the pixel layout description in the analysis framework and results for efficiencies are presented in this work.
Keywords: CERN; HL-LHC; Pixel detectors; ATLAS; Diamond detectors
 
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