Chimie et neutrinos

Cet article illustre la synergie qui existe entre la chimie et la détection des neutrinos, ces particules élémentaires dont l'existence fut confirmée grâce à l'invention des détecteurs à liquide scintillant par des chimistes. Les progrès de ces détecteurs sont issus des recherches des chimistes. La résolution de l'énigme des neutrinos solaires fut rendue possible entre autres par l'obtention d'une extrême pureté radiochimique des différentes cibles utilisées

Quintessence, inflation and baryogenesis from a single pseudo-Nambu-Goldstone boson

We exhibit a model in which a single pseudo-Nambu-Goldstone boson explains dark energy, inflation and baryogenesis. The model predicts correlated signals in future collider experiments, WIMP searches, proton decay experiments, dark energy probes, and the PLANCK satellite CMB measurements.Comment: 16 pages, 3 color figure

MEMPHYS:A large scale water Cerenkov detector at Fr\'ejus

A water \v{C}erenkov detector project, of megaton scale, to be installed in the Fr\'ejus underground site and dedicated to nucleon decay, neutrinos from supernovae, solar and atmospheric neutrinos, as well as neutrinos from a super-beam and/or a beta-beam coming from CERN, is presented and compared with competitor projects in Japan and in the USA. The performances of the European project are discussed, including the possibility to measure the mixing angle $\theta_{13}$ and the CP-violating phase $\delta$.Comment: 1+33 pages, 14 figures, Expression of Interest of MEMPHYS projec

CFD for the Study of the Multiphase Flow and Mass Transfer in a Stirred Tank Reactor for the Screening of Shaped Catalysts

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Low lying S=-1 excited baryons and chiral symmetry

The s-wave meson-baryon interaction in the $S = -1$ sector is studied by means of coupled-channels, using the lowest-order chiral Lagrangian and the N/D method to implement unitarity. The loops are regularized using dimensional renormalization. In addition to the previously studied $\Lambda (1405)$, employing this chiral approach leads to the dynamical generation of two more s-wave hyperon resonances, the $\Lambda(1670)$ and $\Sigma(1620)$ states. We make comparisons with experimental data and look for poles in the complex plane obtaining the couplings of the resonances to the different final states. This allows us to identify the $\Lambda (1405)$ and the $\Lambda(1670)$ resonances with $\bar{K}N$ and $K\Xi$ quasibound states, respectively.Comment: 12 pages, 2 figures, revised version to appear in Phys. Lett. B, errata corrected: modulus of coupling contants is modulus square

Diffuse supernova neutrinos: oscillation effects, stellar cooling and progenitor mass dependence

We estimate the diffuse supernova neutrino background (DSNB) using the recent progenitor-dependent, long-term supernova simulations from the Basel group and including neutrino oscillations at several post-bounce times. Assuming multi-angle matter suppression of collective effects during the accretion phase, we find that oscillation effects are dominated by the matter-driven MSW resonances, while neutrino-neutrino collective effects contribute at the 5-10% level. The impact of the neutrino mass hierarchy, of the time-dependent neutrino spectra and of the diverse progenitor star population is 10% or less, small compared to the uncertainty of at least 25% of the normalization of the supernova rate. Therefore, assuming that the sign of the neutrino mass hierarchy will be determined within the next decade, the future detection of the DSNB will deliver approximate information on the MSW-oscillated neutrino spectra. With a reliable model for neutrino emission, its detection will be a powerful instrument to provide complementary information on the star formation rate and for learning about stellar physics.Comment: 19 pages, including 4 figures and 1 table. Clarifying paragraphs added; results unchanged. Matches published version in JCA

Event categories in the EDELWEISS WIMP search experiment

Four categories of events have been identified in the EDELWEISS-I dark matter experiment using germanium cryogenic detectors measuring simultaneously charge and heat signals. These categories of events are interpreted as electron and nuclear interactions occurring in the volume of the detector, and electron and nuclear interactions occurring close to the surface of the detectors(10-20 mu-m of the surface). We discuss the hypothesis that low energy surface nuclear recoils,which seem to have been unnoticed by previous WIMP searches, may provide an interpretation of the anomalous events recorded by the UKDMC and Saclay NaI experiments. The present analysis points to the necessity of taking into account surface nuclear and electron recoil interactions for a reliable estimate of background rejection factors.Comment: 11 pages, submitted to Phys. Lett.

First Results of the EDELWEISS WIMP Search using a 320 g Heat-and-Ionization Ge Detector

The EDELWEISS collaboration has performed a direct search for WIMP dark matter using a 320 g heat-and-ionization cryogenic Ge detector operated in a low-background environment in the Laboratoire Souterrain de Modane. No nuclear recoils are observed in the fiducial volume in the 30-200 keV energy range during an effective exposure of 4.53 kg.days. Limits for the cross-section for the spin-independent interaction of WIMPs and nucleons are set in the framework of the Minimal Supersymmetric Standard Model (MSSM). The central value of the signal reported by the experiment DAMA is excluded at 90% CL.Comment: 14 pages, Latex, 4 figures. Submitted to Phys. Lett.

Review of Reactor Antineutrino Experiments

As discussed elsewhere, the measurement of a non-zero value for $\theta_{13}$ would open up a wide range of possibilities to explore CP-violation and the mass hierarchy. Experimental methods to measure currently the unknown mixing angle $\theta_{13}$ include accelerator searches for the $\nu_{e}$ appearance and precise measurements of reactor antineutrino disappearance. The reactor antineutrino experiments are designed to search for a non-vanishing mixing angle $\theta_{13}$ with unprecedented sensitivity. This document describes current reactor antineutrino experiments and synergy between accelerator searches for the $\nu_{e}$ appearance and precise measurements of reactor antineutrino disappearance.Comment: 8 pages, 2 figures, Review talk given at NuFact 2011, XIIIth InternationalWorkshop on Neutrino Factories, Super beams and Beta beams, CERN/UNIGE, Geneva, Switzerland, August 1-6, 201

CFD for the Study of the Multiphase Flow and Mass Transfer in a Stirred Tank Reactor for the Screening of Shaped Catalysts

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