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Étude et optimisation de la voie ionisation dans
l'expérience EDELWEISS de détection directe de la
matière noire

Abstract : The EDELWEISS experiment is aiming at the detection of Weakly Interactive Massive Particles (WIMPs), today's most favoured candidates for solving the dark matter issue. Background ionising particles are identified thanks to the simultaneous measurement of heat and ionisation in the detectors. The main limitation to this method is coming from the ionisation measurement, charge collection being less efficient in some part of the detectors known as «dead» areas. The specificity of the measurement is due to the use of very low temperatures and low collection fields. This thesis is dedicated to the study of carrier trapping. It involves time-resolved charge measurements as well as a simulation code adapted to the specific physical conditions. We first present results concerning charge trapping at the free surfaces of the detectors. Our method allows to build a surface-charge in a controlled manner by irradiation with a strong radioactive source. This charge is then caracterised with a weaker source which acts as a probe. In a second part of the work, bulk-trapping characteristics are deduced from charge collection efficiency measurements, and by an original method based on event localisation in the detector. The results show that a large proportion of the doping impurities are ionised, as indicated independently by the study of degradation by space-charge build-up. In this last part, near-electrodes areas are found to contain large densities of charged trapping centres, in connection with dead-layer effects.
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Contributor : Benjamin Censier <>
Submitted on : Tuesday, October 24, 2006 - 3:15:31 PM
Last modification on : Wednesday, September 16, 2020 - 4:06:33 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 6:10:54 PM


  • HAL Id : tel-00109453, version 1



Benjamin Censier. Étude et optimisation de la voie ionisation dans
l'expérience EDELWEISS de détection directe de la
matière noire. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Paris Sud - Paris XI, 2006. Français. ⟨tel-00109453⟩



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