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Search Results: 1 - 10 of 189922 matches for " G. Gerbier "
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Note on a 'hint' for an annual modulation signature of a 60 GeV WIMP
G. Gerbier,J. Mallet,L. Mosca,C. Tao
Physics , 1997,
Abstract: In a recent presentation at the TAUP97 conference about the analysis of data from a NaI(Tl) 100 kg underground detector run at the Gran Sasso Laboratory by the DAMA/NaI group, the speaker concluded there was a hint for a WIMP of mass 60 GeV with a cross section on proton of 10-5 pb (Spin Independent coupling) (see also ROM2F/97/33). Even if no claim of any definite signal is made, such a statement is strong enough to deserve a critical look. The present note puts forward a few arguments which point towards a largely overestimated statistical significance of the effect, an inconsistency in the energy distribution and several experimental effects which could easily mimic the observed excess. The conclusion is that, in no way, the presented result can be considered as a hint of a WIMP annual modulation.
Note about a second "evidence" for a WIMP annual modulation
G. Gerbier,J. Mallet,L. Mosca,C. Tao
Physics , 1999,
Abstract: This note, with its five questions, is intended to contribute to a clarification about a claimed "evidence" by the DAMA group of an annual modulation of the counting rate of a Dark Matter NaI(Tl) detector as due to a neutralino (SUSY-LSP) Dark Matter candidate.
Ultra Low Energy Results and Their Impact to Dark Matter and Low Energy Neutrino Physics  [PDF]
E. Bougamont, P. Colas, J. Derre, I. Giomataris, G. Gerbier, M. Gros, P. Magnier, X. F. Navick, P. Salin, I. Savvidis, G. Tsiledakis, J. D. Vergados
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.31008
Abstract: We present ultra low energy results taken with the novel Spherical Proportional Counter. The energy threshold has been pushed down to about 25 eV and single electrons are clearly collected and detected. To reach such a performance two low energy calibration systems have been successfully developed: a pulsed UV lamp extracting photoelectrons from the inner surface of the detector and various radioactive sources allowing low energy peaks through fluorescence processes. The bench mark result is the observation of a well resolved peak at 270 eV due to carbon fluorescence, which is a unique performance for such large massive detector. It opens up a new window in dark matter and low energy neutrino searches and it may allow the detection of neutrinos from a nuclear reactor or from supernova via neutrino-nucleus elastic scattering.
Annie Renonciat (dir.), Voir/Savoir. La pédagogie par l’image aux temps de l’imprimé, du xvie au xxe siècle
Laurent Gerbier
Strenae : Recherches sur les Livres et Objets Culturels de l'Enfance , 2012,
Abstract: Cet ouvrage dirigé par Annie Renonciat réunit à la fois le catalogue de l’exposition La pédagogie par l’image au temps de l’imprimé , présentée au musée national de l’éducation de Rouen de 2008 à 2011, et les actes partiels du XIIIe symposium des musées de l’éducation, Images et pédagogie. Perspectives internationales , qui s’est tenu à Rouen en juillet 2009. Le volume est ainsi organisé en deux grandes parties : la première partie, qui constitue le catalogue à proprement parler, reprod...
Laurent Gerbier
Astérion , 2005,
Abstract: Les cinq études qui sont ici réunies ont fait l'objet d'une communication lors d'une journée d'étude intitulée Médecine et philosophie de l'Antiquité à l'age classique , qui a eu lieu à l'Institut de Biologie Moléculaire et d'Ingénierie Génétique (IBMIG) de Poitiers, le 12 mai 2001. Cette journée, co-organisée par le CERPHI, la Société Chauvinoise de Philosophie (SCP) et l'IBMIG, est la première d'un cycle de quatre journées annuelles consacré aux rapports entre médecine et philosophie.Ce ...
La politique et la médecine : une figure platonicienne et sa relecture averro ste
Laurent Gerbier
Astérion , 2005,
Abstract: L'art médical est fréquemment utilisé par Platon pour penser de fa on analogique la construction de la science politique et ses difficultés. Une lecture comparée des usages de cette analogie dans le Gorgias et le Politique permet de montrer de quelle fa on Platon utilise cette analogie, et à quel moment précis il s'en défait pour indiquer la différence entre un art des cas (la médecine) et un art des codes (la politique). Au contraire, Averroès, dans son Exposition sur la République de Platon, reprend l'analogie entre médecine et politique d'un point de vue épistémologique, pour mettre en évidence l'identique articulation interne que connaissent ces deux disciplines, et qui permet d'y distinguer chaque fois un art et une science, ou une pratique et une théorie. Averroès se présente ainsi, dans la mesure même où il contourne le problème soulevé par Platon, comme l'initiateur d'une longue tradition d'usage de l'analogie médico-politique, qui va se poursuivre du XIIIe au XVIe siècles pour élucider la structure épistémologique de la science politique.
Boson Mott insulators at finite temperatures
Fabrice Gerbier
Physics , 2007, DOI: 10.1103/PhysRevLett.99.120405
Abstract: We discuss the finite temperature properties of ultracold bosons in optical lattices in the presence of an additional, smoothly varying potential, as in current experiments. Three regimes emerge in the phase diagram: a low-temperature Mott regime similar to the zero-temperature quantum phase, an intermediate regime where MI features persist, but where superfluidity is absent, and a thermal regime where features of the Mott insulator state have disappeared. We obtain the thermodynamic functions of the Mott phase in the latter cases. The results are used to estimate the temperatures achieved by adiabatic loading in current experiments. We point out the crucial role of the trapping potential in determining the final temperature, and suggest a scheme for further cooling by adiabatic decompression.
Quasi-1D Bose-Einstein condensates in the dimensional crossover regime
Fabrice Gerbier
Physics , 2004, DOI: 10.1209/epl/i2004-10035-7
Abstract: We study theoretically the dimensional crossover from a three-dimensional elongated condensate to a one-dimensional condensate as the transverse degrees of freedom get frozen by tight confinement, in the limit of small density fluctuations, i.e. for a strongly degenerate gas. We compute analytically the radially integrated density profile at low temperatures using a local density approximation, and study the behavior of phase fluctuations with the transverse confinement. Previous studies of phase fluctuations in trapped gases have either focused on the 3D elongated regimes or on the 1D regime. The present approach recovers these previous results and is able to interpolate between them. We show in particular that in this strongly degenerate limit the shape of the spatial correlation function is insensitive to the transverse regime of confinement, pointing out to an almost universal behavior of phase fluctuations in elongated traps.
Measuring topology in a laser-coupled honeycomb lattice: From Chern insulators to topological semi-metals
N. Goldman,E. Anisimovas,F. Gerbier,P. Ohberg,I. B. Spielman,G. Juzeliunas
Physics , 2012, DOI: 10.1088/1367-2630/15/1/013025
Abstract: Ultracold fermions trapped in a honeycomb optical lattice constitute a versatile setup to experimentally realize the Haldane model [Phys. Rev. Lett. 61, 2015 (1988)]. In this system, a non-uniform synthetic magnetic flux can be engineered through laser-induced methods, explicitly breaking time-reversal symmetry. This potentially opens a bulk gap in the energy spectrum, which is associated with a non-trivial topological order, i.e., a non-zero Chern number. In this work, we consider the possibility of producing and identifying such a robust Chern insulator in the laser-coupled honeycomb lattice. We explore a large parameter space spanned by experimentally controllable parameters and obtain a variety of phase diagrams, clearly identifying the accessible topologically non-trivial regimes. We discuss the signatures of Chern insulators in cold-atom systems, considering available detection methods. We also highlight the existence of topological semi-metals in this system, which are gapless phases characterized by non-zero winding numbers, not present in Haldane's original model.
Low energy neutron propagation in MCNPX and GEANT4
R. Lemrani,M. Robinson,V. A. Kudryavtsev,M. De Jesus,G. Gerbier,N. J. C. Spooner
Physics , 2006, DOI: 10.1016/j.nima.2005.12.238
Abstract: Simulations of neutron background from rock for underground experiments are presented. Neutron propagation through two types of rock, lead and hydrocarbon material is discussed. The results show a reasonably good agreement between GEANT4, MCNPX and GEANT3 in transporting low-energy neutrons.
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