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| Home > Publications database > Development of a Novel Diamond Based Detector for Machine Induced Background and Luminosity Measurements |
| Book/Report/Dissertation / PhD Thesis | PUBDB-2017-06875 |
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2017
Verlag Deutsches Elektronen-Synchrotron
Hamburg
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Please use a persistent id in citations: doi:10.3204/PUBDB-2017-06875
Report No.: DESY-THESIS-2017-030
Abstract: The Large Hadron Collider (LHC) is the largest particle accelerator and storage ring in the world, used to investigate fundamentals of particle physics and to develop at the same time the technology of accelerators and detectors. Four main experiments, located around the LHC ring, provide insight into the nature of particles and search for answers to as yet unexplained phenomena in the universe. These four experiments are ATLAS (A Toroidal LHC Apparatus), ALICE (A Large Ion Collider Experiment), CMS (Compact Muon Solenoid) and LHCb (LHC beauty). Two proton or heavy ion beams circulate in the LHC and are brought into collision in the four experiments.The physics potential of each experiment is determined by the luminosity, which is a ratio of the number of the events during a certain time period to the cross section of a physics process. A measurement of the luminosity is therefore essential to determine the cross section of interesting physics processes. In addition, safe and high-quality data-taking requires stable beam conditions with almost no beam losses. So-called beam loss monitors are installed in the LHC rings to monitor beam losses around the LHC. Each experiment has in addition its own detectors to measure beam losses, hereafter called machine induced background. One such detector is installed in CMS, the Fast Beam Condition Monitor (BCM1F). Based on diamond sensors it was designed and built to measure both, the luminosity and the machine induced background. BCM1F ran smoothly during the first LHC running period from 2009-2012 and delivered valuable beam loss and luminosity information to the control rooms of CMS and LHC. At the end of 2012 the LHC was shut down for an upgrade to improve the performance by increasing the proton energy from 4 TeV to 7 TeV and decreasing the proton bunch spacing from 50 ns to 25 ns. Due to the success of BCM1F an upgrade of its sensors and readout components was planned in order to fulfil the new requirements. The upgrade of the sensors comprises a two pad instead of one pad metallization. 24 instead of the previous 8 single crystal diamond sensors were foreseen for the new BCM1F to enhance the robustness and redundancy. To instrument BCM1F, 59 sensors were electrically characterized by measuring the leakage current, signal stability and charge collection efficiency. Quality criteria were defined to select sensors for the final installation. An overview of these measurements including a summary of the results is given in this thesis. In addition, an upgraded amplifier was developed within the collaboration in 130 nm CMOS technology. It has a peaking time of 7 ns instead of the 22 ns of the one previously installed. A BCM1F prototype comprising a two pad sensor and the upgraded amplifier was tested at the DESY-II accelerator in a 5 GeV electron beam. Results of these test-beam measurements are presented in this thesis as well as simulations to interpret the measurements. The installation of the upgraded BCM1F was completed in 2014. In 2015 BCM1F was commissioned and started to measure luminosity and machine induced background. At the end, the thesis will describe both types of measurements with the focus on machine induced background demonstrating the functionality of BCM1F.
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