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Détection directe de matière noire avec l’expérience EDELWEISS-III : étude des signaux induits par le piégeage de charges, analyse de données et caractérisation de la sensibilité des détecteurs cryogéniques aux WIMPs de basse masse

Abstract : The EDELWEISS-III experiment is dedicated to direct dark matter searches aiming at detecting WIMPS. These massive particles should account for more than 80% of the mass of the Universe and be detectable through their elastic scattering on nuclei constituting the absorber of a detector. As the expected WIMP event rate is extremely low (<1/kg/year), a double measurement heat/ionization is performed to discriminate electronic recoils originating from _ and backgrounds and nuclear recoils induced by neutrons and WIMPs. The first part of the thesis work consisted in studying the signals induced by charge carrier trapping. An analytical model of its impact on both ionization and heat signals is presented. The model predictions, through their agreement with both data and a numerical simulation, lead to various applications : improvement of the resolutions, statistical sensitivity to energy deposit depths, characterization of trapping within the crystals. The analysis of the Run308 data is detailed and its results are interpreted in terms of an exclusion limit on the WIMP-nucleon cross section (SI). This study brings to light the presence of a limiting neutron background for high mass WIMP searches (>20GeV). Finally, a study dedicated to the optimization of solid cryogenic detectors to low mass WIMP searches is presented. This study is performed on simulated data using a statistical test based on a profiled likelihood ratio that allows for statistical background subtraction and spectral shape discrimination. This study combined with results from Run308, has lead the EDELWEISS experiment to favor low mass WIMP searches (<20GeV)
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https://tel.archives-ouvertes.fr/tel-01273303
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Submitted on : Friday, February 12, 2016 - 11:35:54 AM
Last modification on : Tuesday, November 19, 2019 - 2:44:25 AM
Long-term archiving on: : Friday, May 13, 2016 - 12:41:42 PM

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Quentin Arnaud. Détection directe de matière noire avec l’expérience EDELWEISS-III : étude des signaux induits par le piégeage de charges, analyse de données et caractérisation de la sensibilité des détecteurs cryogéniques aux WIMPs de basse masse. Analyse de données, Statistiques et Probabilités [physics.data-an]. Université Claude Bernard - Lyon I, 2015. Français. ⟨NNT : 2015LYO10199⟩. ⟨tel-01273303⟩

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