Commissioning of the ATLAS Insertable B-Layer and first operation experience

Abstract

Todays research in particle physics offers a wide field of opportunities for scientists from a variety of different subjects. Discoveries can only be made, with hundreds up to thousands of people working together in collaborations. Designing high precision detectors that can be up to several stories tall, followed by production, construction, commissioning and successful operation is only achievable with the combined effort of skilled and experienced detector physicists and engineers, while the vast amount of data recorded with those detectors calls for specialists in data analysis which are able to find the needle in a haystack or in other words the higgs in a sea of underground events. One of the biggest science collaborations worldwide is the ATLAS collaboration with more than 5000 members from around 180 institutes. ATLAS is one of four big particle physics experiments at the LHC. Its tracking system has been upgraded with a new innermost layer, referred to as Insertable B-Layer (IBL), in 2014. This thesis will focus on the construction, commissioning and first year of operation of the IBL detector and give a brief outlook on upgrade plans for the tracking system. The performance of the IBL and its services was observed before and after each step of its construction. Quality assurance measurements were performed to select the best working staves for the IBL construction. A system test was performed to verify the correct functionality of the final setup were the IBL was built on. A thorough commissioning testing the supply chain, the readout and the performance of complete detector was carried out in a clean room and repeated after installation in ATLAS. Several steps of re-testing took place after the IBL was exposed to thermal stress. The results of each commissioning step will be presented and discussed. During the first year of operating the IBL, an increase of the low voltage currents in the readout chips was observed. A model to understand this increase will be introduced as well as measurements that were used to develop an operation guideline to protect the detector while continuing to take data. The last part of this thesis will give a brief introduction to an alternative method for module hybridisation that was investigated as a possible option for the next upgrade of the ATLAS tracking system.