Together with the ongoing works on preparations of High-Luminosity LHC, there is a need to enhance the performance of various experiments on the collider as well. This is also the case of the experiment ATLAS and its subdetectors such as Inner Detector which will be completely replaced by new all-silicon Inner Tracker (ITk). This thesis deals with computer simulations of silicon strip detec- tors for ATLAS Upgrade ITk. For this purpose, we are using framework AllPix2 . It enables to simulate everything from the interaction of the particle with silicon, charge propagation in electric and magnetic fields, charge collection, up to signal digitization. We focused mostly on three aspects in the simulations. The first is a precise characterization of used detectors, the second is a simulation of a test beam measurements and the third one is a simulation of test measurements with a radioactive beta source. We also discussed the possibility of simulation of test measurements with a laser. These simulations are important not only because they help us to better understand processes happening inside the detector, but they are also used as a validation of testing measurements. As a result of this, we are able to point out the effects of the experimental setup (or detector itself) which have an impact on measured...

Abstract Research on X-ray imaging sensors and systems have been carried out for several decades. To make these X-ray scanners smaller with better performance and higher operating speed is an important subject for scientific research and industrial applications. This thesis covers a whole X-ray line-scan camera system. Special attention is given to the smart sensor micromodule design and processing technology. The smart sensor micromodule is an integrated sensor card that includes both silicon X-ray sensor array and signal-processing integrated circuits, which can perform the functions of both an optical sensor and an analog signal processor. Digital signal processing (DSP) made by application specific integrated circuits (ASICs) is also covered in this thesis. Processing technology of the photodiode array, design of the integrated circuit, design and packaging of the micromodules are presented in this thesis. The mechanism of photodiode leakage current is studied in detail. Measured results show that the leakage current level of the photodiode array achieves 80 pA/cm2 under zero bias condition, which outperforms the best photodiode reported so far. The algorithm of the digital signal processing is also studied. The X-ray scanning system can achieve 2 m/s scanning speed with a spatial resolution of 400 mm.

As of writing this thesis there are two detectors at TRIUMF’s DRAGON facility which directly measure the kinetic energy (E) of heavy ions at the focal plane of its recoil separator. These are an ionization chamber and a double-sided-silicon-strip detector (DSSSD). The ionization chamber has in- ferior resolution to the DSSSD but can discriminate isobaric contaminants in a E-∆E spectrum. A DSSSD has superior energy resolution and timing but cannot discriminate isobaric contaminants in many cases. A hybrid ioniza- tion chamber / double-sided-silicon-strip detector has been designed using the GEANT4 simulation package that combines the strengths of both these detec- tor types. This hybrid detector design consists of an ionization chamber set in front of a DSSSD positioned at the end of the beamline of the recoil separator. The design presented here is specific to DRAGON’s needs but can conceiv- ably be re-purposed in other environments requiring heavy ion detection and identification and may be useful in fields such as health physics. / Thesis / Master of Science (MSc)

Neste trabalho são apresentados os estudos das condições de resposta de um diodo de Si, com estrutura de múltiplos anéis de guarda, na detecção e espectrometria de partículas alfa. Este diodo foi fabricado por meio do processo de implantação iônica (Al/p+/n/n+/Al) em um substrato de Si do tipo n com resistividade de 3 kohm•cm, 300 mícrons de espessura e área útil de 4 mm2. Para usar este diodo como detector, a face n+ deste dispositivo foi polarizada reversamente, o primeiro anel de guarda aterrado e os sinais elétricos extraídos da face p+. Estes sinais eram enviados diretamente a um pré-amplificador desenvolvido em nosso laboratório, baseado no emprego do circuito híbrido A250 da Amptek, seguido da eletrônica nuclear convencional. Os resultados obtidos com este sistema na detecção direta de partículas alfa do Am-241evidenciaram excelente estabilidade de resposta com uma elevada eficiência de detecção (= 100 %). O desempenho deste diodo na espectrometria de partículas alfa foi estudado priorizando-se a influência da tensão de polarização, do ruído eletrônico, da temperatura e da distância fonte-detector na resolução em energia. Os resultados mostraram que a maior contribuição para a deterioração deste parâmetro é devida à espessura da camada morta do diodo (1 mícron). No entanto, mesmo em temperatura ambiente, a resolução medida (FWHM = 18,8 keV) para as partículas alfa de 5485,6 keV (Am-241) é comparável àquelas obtidas com detectores convencionais de barreira de superfície freqüentemente utilizados em espectrometria destas partículas. / In this work are presented the studies about the response of a multi-structure guard rings silicon diode for detection and spectrometry of alpha particles. This ion-implanted diode (Al/p+/n/n+/Al) was processed out of 300 micrometers thick, n type substrate with a resistivity of 3 kohm•cm and an active area of 4 mm2. In order to use this diode as a detector, the bias voltage was applied on the n+ side, the first guard ring was grounded and the electrical signals were readout from the p+ side. These signals were directly sent to a tailor made preamplifier, based on the hybrid circuit A250 (Amptek), followed by a conventional nuclear electronic. The results obtained with this system for the direct detection of alpha particles from Am-241 showed an excellent response stability with a high detection efficiency (= 100 %). The performance of this diode for alpha particle spectrometry was studied and it was prioritized the influence of the polarization voltage, the electronic noise, the temperature and the source-diode distance on the energy resolution. The results showed that the major contribution for the deterioration of this parameter is due to the diode dead layer thickness (1 micrometer). However, even at room temperature, the energy resolution (FWHM = 18.8 keV) measured for the 5485.6 MeV alpha particles (Am-241) is comparable to those obtained with ordinary silicon barrier detectors frequently used for these particles spectrometry.

Neste trabalho são apresentados os estudos das condições de resposta de um diodo de Si, com estrutura de múltiplos anéis de guarda, na detecção e espectrometria de partículas alfa. Este diodo foi fabricado por meio do processo de implantação iônica (Al/p+/n/n+/Al) em um substrato de Si do tipo n com resistividade de 3 kohm•cm, 300 mícrons de espessura e área útil de 4 mm2. Para usar este diodo como detector, a face n+ deste dispositivo foi polarizada reversamente, o primeiro anel de guarda aterrado e os sinais elétricos extraídos da face p+. Estes sinais eram enviados diretamente a um pré-amplificador desenvolvido em nosso laboratório, baseado no emprego do circuito híbrido A250 da Amptek, seguido da eletrônica nuclear convencional. Os resultados obtidos com este sistema na detecção direta de partículas alfa do Am-241evidenciaram excelente estabilidade de resposta com uma elevada eficiência de detecção (= 100 %). O desempenho deste diodo na espectrometria de partículas alfa foi estudado priorizando-se a influência da tensão de polarização, do ruído eletrônico, da temperatura e da distância fonte-detector na resolução em energia. Os resultados mostraram que a maior contribuição para a deterioração deste parâmetro é devida à espessura da camada morta do diodo (1 mícron). No entanto, mesmo em temperatura ambiente, a resolução medida (FWHM = 18,8 keV) para as partículas alfa de 5485,6 keV (Am-241) é comparável àquelas obtidas com detectores convencionais de barreira de superfície freqüentemente utilizados em espectrometria destas partículas. / In this work are presented the studies about the response of a multi-structure guard rings silicon diode for detection and spectrometry of alpha particles. This ion-implanted diode (Al/p+/n/n+/Al) was processed out of 300 micrometers thick, n type substrate with a resistivity of 3 kohm•cm and an active area of 4 mm2. In order to use this diode as a detector, the bias voltage was applied on the n+ side, the first guard ring was grounded and the electrical signals were readout from the p+ side. These signals were directly sent to a tailor made preamplifier, based on the hybrid circuit A250 (Amptek), followed by a conventional nuclear electronic. The results obtained with this system for the direct detection of alpha particles from Am-241 showed an excellent response stability with a high detection efficiency (= 100 %). The performance of this diode for alpha particle spectrometry was studied and it was prioritized the influence of the polarization voltage, the electronic noise, the temperature and the source-diode distance on the energy resolution. The results showed that the major contribution for the deterioration of this parameter is due to the diode dead layer thickness (1 micrometer). However, even at room temperature, the energy resolution (FWHM = 18.8 keV) measured for the 5485.6 MeV alpha particles (Am-241) is comparable to those obtained with ordinary silicon barrier detectors frequently used for these particles spectrometry.

Beta Source Tests of Semiconductor Detectors ITk for ATLAS Upgrade Abstract: The ATLAS experiment is due to undergo a major upgrade for the High Luminosity phase of the LHC operation. In particular, the current tracking system (ID) will be replaced by full-silicon ITk. IPNP laboratories are involved in R&D of SCT detector modules for ITk. Low-temperature β-source tests of the R0 FR 5 module prototype were the main focus of this thesis. After testing the cooling cycle, 11 threshold scans were performed on two ABC130 chips, yielding the median collected charge ranging between 2.9 ± 0.2 fC and 3.1 ± 0.2 fC for chip #6 at SNR from 16.0 ± 1.0 at 24 ◦ C to 22.7 ± 1.5 at −15 ◦ C. No trend with temperature was observed outside the error bars. The results are in accordance with previous similar measurements. Question of fitting the median collected charge in various units was adressed and equivalence of the fits was determined. The ability of IPNP laboratories to perform low-temperature β-source tests was proven.

During my time as a PhD student at the Physics of Medical Imaging group at KTH, I have taken part in the work of developing a photon counting spectrally resolved silicon detector for clinical computed tomography. This work has largely motivated the direction of my research, and is the main reason for my focus on certain issues. Early in the work, a need to quantify and optimize the performance of a spectrally resolved detector was identified. A large part of my work have thus consisted of reviewing conventional methods used for performance quantification and optimization in computed tomography, and identifying which are best suited for the characterization of a spectrally resolved system. In addition, my work has included comparisons of conventional systems with the detector we are developing. The collected result after a little more than four years of work are four publications and three conference papers. This compilation thesis consists of five introductory chapters and my four publications. The introductory chapters are not self-contained in the sense that the theory and results from all my published work are included. Rather, they are written with the purpose of being a context in which the papers should be read. The first two chapters treat the general purpose of the introductory chapters, and the theory of computed tomography including the distinction between conventional, non-spectral, computed tomography, and different practical implementations of spectral computed tomography. The second chapter consists of a review of the conventional methods developed for quantification and optimization of image quality in terms of detectability and signal-to-noise ratio, part of which are included in my published work. In addition, the theory on which the method of material basis decomposition is based on is presented, together with a condensed version of the results from my work on the comparison of two systems with fundamentally different practical solutions for material quantification. In the fourth chapter, previously unpublished measurements on the photon counting spectrally resolved detector we are developing are presented, and compared to Monte Carlo simulations. In the fifth and final chapter, a summary of the appended publications is included. / <p>QC 20150303</p>

This thesis is about the alignment of vertex semiconductor detectors of the Belle II experiment. It is divided into several sections. The first part introduces the Belle II experiment as a new generation B- factory, with its ambitious plans of data taking and physical analysis. The second part follows with a more detailed description of Belle II detector and software tools designed for their alignment and calibration. The central part of the thesis describes physical processes used for calibration of the vertex detector, connected with the search of an optimal solution for run-time monitoring and calibration of the detector. We also tested the effect of misalignment on the Belle II tracking software. The following part gives results of the study of misalignment effects on physical observables related to analysis of selected physical channels. The last part describes the development of a data quality monitoring tool for the tracking system. The tools has to provide a run-time diagnostic of misalignment and miscalibration by monitoring the precision and accuracy of reconstruction of physical observables. Powered by TCPDF (www.tcpdf.org)

The semiconductor detectors of ATLAS experiment at CERN are exposed to high radiation for a long time, which reduces their efficiency. They need to be replaced and, if necessary, modernized. Nowadays, the entire Large Hadron Collider is planned to improve. Its luminosity will increase. During this shut- down, the detectors of ATLAS experiment will also be upgraded. This thesis is focused on strip detectors of a new inner detector of ATLAS experiment called ITk. For the correct interpretation of the measured results, it is important to know the detector's response. Test of detector response is, therefore, an important part of the process of developing. In this thesis, we focused on detectors' edges, where we assumed a different shape of the electric field, which may cause a different response. We chose the laser test because it is a position-sensitive measurement. 1

Energy resolution characteristics of silicon surface barrier detector signals amplified by different preamplifiers and spectroscopic amplifiers have been studied. The characterization has been done using alpha particles from an 241Am source and spontaneous fission fragments from two Cf sources. The alpha and spontaneous fission activities of the sources have been measured and the isotopic compositions, ages, and initial activities of the two Cf sources have been calculated using the results from the activity measurements. 82.3% and 82.5% of the spontaneous fission activity of the two sources is found to originate from 252Cf. Heavy ion detection properties of two Si detector setups have been determined by measuring spontaneous fission fragments from one of the Cf sources in coincidence. The mass distribution of fission fragments is derived from the pulse spectra of the coincidence measurements. The conditions for future time resolution measurements have been established. Inquiries on commercially available ultra-thin Si detectors have been made. The purpose is to upgrade detector telescopes to lower the energy threshold of ΔE-ΔE-E identification of particles from neutroninduced nuclear reactions. Three manufacturers of Si detectors with thickness 20-25 µm and active area around 450 mm2 have been listed together with properties of the three offered detectors.