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Identification des événements de surface dans les bolomètres équipés de couches minces d'isolant d'Anderson, application à la détection directe de matière noire

Abstract : In direct detection of WIMPS (a plausible candidate for dark matter) experiments the detector plays a very essential rule. The EDELWEISS experiment uses cryogenic semiconductor detectors to measure the heat (bolometer) and ionization produced by an event. Comparing these two quantities for each event, one can distinguish an "electron recoil" (background other than neutrons) from a "nuclear recoil" events (WIMPS). Meanwhile for the events taking place not far enough from the electrodes, a deficit in charge collection will degrade the detector discrimination ability. We introduced a new method to identify the near surface events, which is based on the detector "heat" transient regime. We use NbxSi1-x Anderson insulator thin layers evaporated directly on the absorber (Ge or sapphire) for analyzing this regime. We find an enhanced transient heat signal for an event less deep than a critical value, dc (~1mm in Ge) comparing to a detector bulk event with identical energy. We could determine this enhancement with respect to the depth of interaction (d< dc) and we have verified that it is valid down to the energy threshold of the detector. We designed a setup in which the thermometers are used for charge collection electrodes simultaneously. We have shown that by this method, one can identify the events giving rise to an incomplete charge collection due to their proximity to the electrodes. This method let us define a fiduciel volume where the discrimination performance is not limited by such events.
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https://tel.archives-ouvertes.fr/tel-00002708
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Submitted on : Thursday, April 10, 2003 - 4:05:34 PM
Last modification on : Wednesday, October 14, 2020 - 4:00:13 AM
Long-term archiving on: : Friday, April 2, 2010 - 6:30:31 PM

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  • HAL Id : tel-00002708, version 1

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Nader Mirabolfathi. Identification des événements de surface dans les bolomètres équipés de couches minces d'isolant d'Anderson, application à la détection directe de matière noire. Cosmologie et astrophysique extra-galactique [astro-ph.CO]. Université Paris Sud - Paris XI, 2002. Français. ⟨tel-00002708⟩

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