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Séminaires et colloques
Séminaire des Doctorants 2014: C. Prahoveanu, Q. Riffard
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Europe/Paris
Grand amphi
Grand amphi
Description
C. Prahoveanu: Investigation of thermoelectric Mg2(Si,Sn) thin films deposited by microwave plasma co-sputtering method
Abstract: In search for materials appropriate for miniaturized thermoelectric materials, thin films of Mg2(Si,Sn) solid solutions have been deposited on SiO2/Si, glass and Ni substrates by microwave plasma-assisted co-sputtering method with a fine control over their stoichiometry. The types of substrates were chosen based on the particularities of a thermoelectric module which comprises both electrodes and insulators. The thermo-mechanical properties and thermal stability of the thin films have been investigated after intermediate temperature thermal treatments. It is shown that the deposition process, as well as the substrates on which the films are grown, determine the subsequent adherence of the films. Also, the metastability of the chosen solid solution leads to a separation into 2 phases at intermediate temperatures that stabilize after the first annealing treatment (623 K). Furthermore, by increasing the temperature of the thermal treatment (773 K), the decomposition of the material is observed, thus establishing the functional temperature range for these solid solutions as thin films.
Q. Riffard: Détection directionnelle de matière sombre avec MIMAC
Abstract: Dark Matter (DM) directional detection is based on the idea that the angular distribution of WIMP (Weakly Interacting Massive Particle) momentum directions should present an anisotropy in galactic coordinates. This anisotropy is due to the relative motion of the solar system with respect to the cold galactic DM halo. Thus, the angular distribution of recoils produced by scattering of WIMPs on nuclei should present an anisotropy pointing towards the constellation Cygnus. Background events are instead isotropically distributed in Galactic coordinates. Using a profile likelihood analysis it has been shown that it is possible to extract a DM signal from background events. As other directional detection experiments, the aim of the MIMAC project is the measurement of nuclear recoil energy and angular distribution to search for this signature.
This strategy requires both a measurement of the recoil energy with a threshold of about 5 keV and 3D recoil tracks down to few millimeters. The MIMAC project, based on a µ-TPC matrix, with CF4 and CHF3, is being developed. In June 2012, a bi-chamber prototype was installed at the LSM (Laboratoire Souterrain de Modane). An analysis of the first months data taking allowed, for the first time, the observation of recoils from the 222Rn progeny.
Abstract: In search for materials appropriate for miniaturized thermoelectric materials, thin films of Mg2(Si,Sn) solid solutions have been deposited on SiO2/Si, glass and Ni substrates by microwave plasma-assisted co-sputtering method with a fine control over their stoichiometry. The types of substrates were chosen based on the particularities of a thermoelectric module which comprises both electrodes and insulators. The thermo-mechanical properties and thermal stability of the thin films have been investigated after intermediate temperature thermal treatments. It is shown that the deposition process, as well as the substrates on which the films are grown, determine the subsequent adherence of the films. Also, the metastability of the chosen solid solution leads to a separation into 2 phases at intermediate temperatures that stabilize after the first annealing treatment (623 K). Furthermore, by increasing the temperature of the thermal treatment (773 K), the decomposition of the material is observed, thus establishing the functional temperature range for these solid solutions as thin films.
Q. Riffard: Détection directionnelle de matière sombre avec MIMAC
Abstract: Dark Matter (DM) directional detection is based on the idea that the angular distribution of WIMP (Weakly Interacting Massive Particle) momentum directions should present an anisotropy in galactic coordinates. This anisotropy is due to the relative motion of the solar system with respect to the cold galactic DM halo. Thus, the angular distribution of recoils produced by scattering of WIMPs on nuclei should present an anisotropy pointing towards the constellation Cygnus. Background events are instead isotropically distributed in Galactic coordinates. Using a profile likelihood analysis it has been shown that it is possible to extract a DM signal from background events. As other directional detection experiments, the aim of the MIMAC project is the measurement of nuclear recoil energy and angular distribution to search for this signature.
This strategy requires both a measurement of the recoil energy with a threshold of about 5 keV and 3D recoil tracks down to few millimeters. The MIMAC project, based on a µ-TPC matrix, with CF4 and CHF3, is being developed. In June 2012, a bi-chamber prototype was installed at the LSM (Laboratoire Souterrain de Modane). An analysis of the first months data taking allowed, for the first time, the observation of recoils from the 222Rn progeny.
In this presentation, we will present the directional search strategy of DM, the MIMAC detector principle, the data analysis from the bi-chamber prototype at Modane and the interpretation of the results.
