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Search Results: 1 - 10 of 13459 matches for " X. Defay "
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Modeling of the evolution of dielectric loss with processing temperature in ferroelectric and dielectric thin oxide films
X. H. Zhu,B. Guigues,E. Defay,M. Aid
Physics , 2008, DOI: 10.1063/1.2999638
Abstract: It was experimentally found that the evolution of dielectric loss with processing temperature displays a common trend in ferroelectric and dielectric thin oxide films: firstly an increase and then a decrease in dielectric loss when the processing temperature is gradually raised. Such a dielectric response of ferroelectric/dielectric thin films has been theoretically addressed in this work. We propose that at the initial stage of the crystallization process in thin films, the transformation from amorphous to crystalline phase should increase substantially the dielectric loss; then, with further increase in the processing temperature, the coalescent growth of small crystalline grains into big ones could be helpful in reducing the dielectric loss by lowering grain boundary densities. The obtained experimental data for (Ba,Sr)TiO3 thin films with 500 nm in thickness were analyzed in terms of the model developed and shown to be in a reasonable agreement with the theoretical results.
Cryogenic silicon detectors with implanted contacts for the detection of visible photons using the Neganov-Luke Effect
X. Defay,E. Mondragon,M. Willers,A. Langenkamper,J. -C. Lanfranchi,A. Munstera,A. Zoller,S. Wawoczny,H. Steiger,F. Hitzler,C. Bruhn,S. Schonert,W. Potzel,M. Chapellier
Physics , 2015,
Abstract: There is a common need in astroparticle experiments such as direct dark matter detection, 0{\nu}\b{eta}\b{eta} (double beta decay without emission of neutrinos) and Coherent Neutrino Nucleus Scattering experiments for light detectors with a very low energy threshold. By employing the Neganov-Luke Effect, the thermal signal of particle interactions in a semiconductor absorber operated at cryogenic temperatures, can be amplified by drifting the photogenerated electrons and holes in an electric field. This technology is not used in current experiments, in particular because of a reduction of the signal amplitude with time which is due to trapping of the charges within the absorber. We present here the first results of a novel type of Neganov-Luke Effect detector with an electric field configuration designed to improve the charge collection within the semiconductor.
Cantilever-based electret energy harvesters
S. Boisseau,G. Despesse,T. Ricart,E. Defay,A. Sylvestre
Physics , 2011, DOI: 10.1088/0964-1726/20/10/105013
Abstract: Integration of structures and functions allowed reducing electric consumptions of sensors, actuators and electronic devices. Therefore, it is now possible to imagine low-consumption devices able to harvest their energy in their surrounding environment. One way to proceed is to develop converters able to turn mechanical energy, such as vibrations, into electricity: this paper focuses on electrostatic converters using electrets. We develop an accurate analytical model of a simple but efficient cantilever-based electret energy harvester. Therefore, we prove that with vibrations of 0.1g (~1m/s^{2}), it is theoretically possible to harvest up to 30\muW per gram of mobile mass. This power corresponds to the maximum output power of a resonant energy harvester according to the model of William and Yates. Simulations results are validated by experimental measurements but the issues of parasitic capacitances get a large impact. Therefore, we 'only' managed to harvest 10\muW per gram of mobile mass, but according to our factor of merit, this puts us in the best results of the state of the art. http://iopscience.iop.org/0964-1726/20/10/105013
A new high-background-rejection dark matter Ge cryogenic detector
A. Broniatowski,X. Defay,E. Armengaud,L. Berge,A. Benoit,O. Besida,J. Blumer,A. Chantelauze,M. Chapellier,G. Chardin,F. Charlieux,S. Collin,O. Crauste,M. De Jesus,P. Di Stefano,Y. Dolgorouki,J. Domange,L. Dumoulin,K. Eitel,J. Gascon,G. Gerbier,M. Gros,M. Hannawald,S. Herve,A. Juillard,H. Kluck,V. Kozlov,R. Lemrani,A. Lubashevskiy,C. Marrache,S. Marnieros,X. -F. Navick,C. Nones,E. Olivieri,P. Pari,B. Paul,S. Rozov,V. Sanglard,S. Scorza,S. Semikh,M. -A. Verdier,L. Vagneron,E. Yakushev
Physics , 2009, DOI: 10.1016/j.physletb.2009.10.036
Abstract: A new design of a cryogenic germanium detector for dark matter search is presented, taking advantage of the coplanar grid technique of event localisation for improved background discrimination. Experiments performed with prototype devices in the EDELWEISS II setup at the Modane underground facility demonstrate the remarkably high efficiency of these devices for the rejection of low-energy $\beta$, approaching 10$^5$ . This opens the road to investigate the range beyond 10$^{-8}$ pb in the WIMP-nucleon collision cross-sections, as proposed in the EURECA project of a one-ton cryogenic detector mass.
First results of the EDELWEISS-II WIMP search using Ge cryogenic detectors with interleaved electrodes
E. Armengaud,C. Augier,A. Benoit,L. Berge,O. Besida,J. Blumer,A. Broniatowski,A. Chantelauze,M. Chapellier,G. Chardin,F. Charlieux,S. Collin,X. Defay,M. De Jesus,P. Di Stefano,Y. Dolgorouki,J. Domange,L. Dumoulin,K. Eitel,J. Gascon,G. Gerbier,M. Gros,M. Hannawald,S. Herve,A. Juillard,H. Kluck,V. Kozlov,R. Lemrani,P. Loaiza,A. Lubashevskiy,S. Marnieros,X-F. Navick,E. Olivieri,P. Pari,B. Paul,S. Rozov,V. Sanglard,S. Scorza,S. Semikh,A. S. Torrento-Coello,L. Vagneron,M-A. Verdier,E. Yakushev,the EDELWEISS Collaboration
Physics , 2009, DOI: 10.1016/j.physletb.2010.03.057
Abstract: The EDELWEISS-II collaboration has performed a direct search for WIMP dark matter with an array of ten 400 g heat-and-ionization cryogenic detectors equipped with interleaved electrodes for the rejection of near-surface events. Six months of continuous operation at the Laboratoire Souterrain de Modane have been achieved. The observation of one nuclear recoil candidate above 20 keV in an effective exposure of 144 kgd is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 1.0x10^-7 pb is excluded at 90%CL for a WIMP mass of 80 GeV/c2. This result demonstrates for the first time the very high background rejection capabilities of these simple and robust detectors in an actual WIMP search experiment.
Monitoring of the thermal neutron flux in the LSM underground laboratory
S. Rozov,E. Armengaud,C. Augier,L. Bergé,A. Benoit,O. Besida,J. Blümer,A. Broniatowski,V. Brudanin,A. Chantelauze,M. Chapellier,G. Chardin,F. Charlieux,S. Collin,O. Crauste,M. De Jesus,X. Defay,P. Di Stefano,Y. Dolgorouki,J. Domange,L. Dumoulin,K. Eitel,D. Filosofov,J. Gascon,G. Gerbier,M. Gros,M. Hannawald,A. Juillard,H. Kluck,V. Kozlov,R. Lemrani,A. Lubashevskiy,C. Marrach,S. Marnieros,X-F. Navick,C. Nones,E. Olivieri,P. Pari,B. Paul,V. Sanglard,S. Scorza,S. Semikh,M-A. Verdier,L. Vagneron,E. Yakushev
Physics , 2010,
Abstract: This paper describes precise measurements of the thermal neutron flux in the LSM underground laboratory in proximity of the EDELWEISS-II dark matter search experiment together with short measurements at various other locations. Monitoring of the flux of thermal neutrons is accomplished using a mobile detection system with low background proportional counter filled with $^3$He. On average 75 neutrons per day are detected with a background level below 1 count per day (cpd). This provides a unique possibility of a day by day study of variations of the neutron field in a deep underground site. The measured average 4$\pi$ neutron flux per cm$^{2}$ in the proximity of EDELWEISS-II is $\Phi_{MB}=3.57\pm0.05^{stat}\pm0.27^{syst}\times 10^{-6}$ neutrons/sec. We report the first experimental observation that the point-to-point thermal neutron flux at LSM varies by more than a factor two.
A detection system to measure muon-induced neutrons for direct Dark Matter searches
V. Yu. Kozlov,E. Armengaud,C. Augier,A. Benoit,L. Berge,O. Besida,J. Blumer,A. Broniatowski,V. Brudanin,A. Chantelauze,M. Chapellier,G. Chardin,F. Charlieux,S. Collin,X. Defay,M. De Jesus,P. Di Stefano,Y. Dolgorouki,J. Domange,L. Dumoulin,K. Eitel,J. Gascon,G. Gerbier,M. Gros,M. Hannawald,S. Herve,A. Juillard,H. Kluck,R. Lemrani,P. Loaiza,A. Lubashevskiy,S. Marnieros,X. -F. Navick,E. Olivieri,P. Pari,B. Paul,S. Rozov,V. Sanglard,S. Scorza,S. Semikh,A. S. Torrento-Coello,L. Vagneron,M-A. Verdier,E. Yakushev
Physics , 2010, DOI: 10.1016/j.astropartphys.2010.06.001
Abstract: Muon-induced neutrons constitute a prominent background component in a number of low count rate experiments, namely direct searches for Dark Matter. In this work we describe a neutron detector to measure this background in an underground laboratory, the Laboratoire Souterrain de Modane. The system is based on 1 m3 of Gd-loaded scintillator and it is linked with the muon veto of the EDELWEISS-II experiment for coincident muon detection. The system was installed in autumn 2008 and passed since then a number of commissioning tests proving its full functionality. The data-taking is continuously ongoing and a count rate of the order of 1 muon-induced neutron per day has been achieved.
Correlation between electric-field-induced phase transition and piezoelectricity in lead zirconate titanate films
V Kovacova,N Vaxelaire,G Le Rhun,P Gergaud,T Schmitz-Kempen,E Defay
Physics , 2015, DOI: 10.1103/PhysRevB.90.140101
Abstract: We observed that electric field induces phase transition from tetragonal to rhombohedral in polycrystalline morphotropic lead zirconate titanate (PZT) films, as reported in 2011 for bulk PZT. Moreover, we evidenced that this field-induced phase transition is strongly correlated with PZT film piezoelectric properties, that is to say the larger the phase transition, the larger the longitudinal piezoelectric coefficient d 33,eff . Although d 33,eff is already comprised between as 150 to 170 pm/V, our observation suggests that one could obtain larger d 33,eff values, namely 250 pm/V, by optimizing the field-induced phase transition thanks to composition fine tuning.
The CRESST Dark Matter Search - Status and Perspectives
The CRESST Collaboration,F. Reindl,G. Angloher,A. Bento,C. Bucci,L. Canonica,X. Defay,A. Erb,F. v. Feilitzsch,N. Ferreiro Iachellini,P. Gorla,A. Gütlein,D. Hauff,J. Jochum,M. Kiefer,H. Kluck,H. Kraus,J. C. Lanfranchi,J. Loebell,A. Münster,C. Pagliarone,F. Petricca,W. Potzel,F. Pr?bst,K. Sch?ffner,J. Schieck,S. Sch?nert,W. Seidel,L. Stodolsky,C. Strandhagen,R. Strauss,A. Tanzke,H. H. Trinh Thi,C. Türko?lu,M. Uffinger,A. Ulrich,I. Usherov,S. Wawoczny,M. Willers,M. Wüstrich,A. Z?ller
Physics , 2015,
Abstract: In the past years the spotlight of the search for dark matter particles widened to the low mass region, both from theoretical and experimental side. We discuss results from data obtained in 2013 with a single detector TUM40. This detector is equipped with a new upgraded holding scheme to efficiently veto backgrounds induced by surface alpha decays. This veto, the low threshold of 0.6keV and an unprecedented background level for CaWO$_4$ target crystals render TUM40 the detector with the best overall performance of CRESST-II phase 2 (July 2013 - August 2015). A low-threshold analysis allowed to investigate light dark matter particles (<3GeV/c$^2$), previously not accessible for other direct detection experiments.
Results on light dark matter particles with a low-threshold CRESST-II detector
The CRESST Collaboration,G. Angloher,A. Bento,C. Bucci,L. Canonica,X. Defay,A. Erb,F. v. Feilitzsch,N. Ferreiro Iachellini,P. Gorla,A. Gütlein,D. Hauff,J. Jochum,M. Kiefer,H. Kluck,H. Kraus,J. C. Lanfranchi,J. Loebell,A. Münster,C. Pagliarone,F. Petricca,W. Potzel,F. Pr?bst,F. Reindl,K. Sch?ffner,J. Schieck,S. Sch?nert,W. Seidel,L. Stodolsky,C. Strandhagen,R. Strauss,A. Tanzke,H. H. Trinh Thi,C. Türko?lu,M. Uffinger,A. Ulrich,I. Usherov,S. Wawoczny,M. Willers,M. Wüstrich,A. Z?ller
Physics , 2015,
Abstract: The CRESST-II experiment uses cryogenic detectors to search for nuclear recoil events induced by the elastic scattering of dark matter particles in CaWO$_4$ crystals. Given the low energy threshold of our detectors in combination with light target nuclei, low mass dark matter particles can be probed with high sensitivity. In this letter we present the results from data of a single detector module corresponding to 52 kg live days. A blind analysis is carried out. With an energy threshold for nuclear recoils of 307 eV we substantially enhance the sensitivity for light dark matter. Thereby, we extend the reach of direct dark matter experiments to the sub-region and demonstrate that the energy threshold is the key parameter in the search for low mass dark matter particles.
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