Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers

Gif-sur-Yvette, France

Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers

Gif-sur-Yvette, France
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Boulade O.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Moreau V.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Mulet P.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Gravrand O.,Sofradir | And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

CEA and SOFRADIR have been manufacturing and characterizing near infrared detectors in the frame of ESA's near infrared large format sensor array roadmap to develop a 2Kx2K large format low flux low noise device for space applications such as astrophysics. These detectors use HgCdTe as the absorbing material and p/n diode technology. The technological developments (photovoltaic technology, readout circuit,.) are shared between CEA/LETI and SOFRADIR, both in Grenoble, while most of the performances are evaluated at CEA/IRFU in Saclay where a dedicated test facility has been developed, in particular to measure very low dark currents. The paper will present the current status of these developments at the end of ESA's NIRLFSA phase 2. The performances of the latest batch of devices meet or are very close to all the requirements (quantum efficiency, dark current, cross talk, readout noise,.) even though a glow induced by the ROIC prevents the accurate measurement of the dark current. The current devices are fairly small, 640x512 15μm pixels, and the next phase of activity will target the development of a full size 2Kx2K detector. From the design and development, to the manufacturing and finally the testing, that type of detector requests a high level of mastering. An appropriate manufacturing and process chain compatible with such a size is needed at industrial level and results obtained with CEA technology coupled with Sofradir industrial experience and work on large dimension detector allow French actors to be confident to address this type of future missions. © 2016 SPIE.


Cirelli M.,CERN | Cirelli M.,French National Center for Scientific Research | Moulin E.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Panci P.,University of Southern Denmark | And 3 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We derive new bounds on decaying dark matter from the gamma ray measurements of (i)the isotropic residual (extragalactic) background by Fermi and (ii)the Fornax galaxy cluster by H.E.S.S. We find that those from (i)are among the most stringent constraints currently available, for a large range of dark matter masses and a variety of decay modes, excluding half-lives up to ∼1026 to few 1027seconds. In particular, they rule out the interpretation in terms of decaying dark matter of the e ± spectral features in PAMELA, Fermi and H.E.S.S., unless very conservative choices are adopted. We also discuss future prospects for CTA bounds from Fornax which, contrary to the present H.E.S.S. constraints of (ii), may allow for an interesting improvement and may become better than those from the current or future extragalactic Fermi data. © 2012 American Physical Society.


Devost D.,Canada France Hawaii Telescope Corporation | Moutou C.,Canada France Hawaii Telescope Corporation | Moutou C.,French National Center for Scientific Research | Manset N.,Canada France Hawaii Telescope Corporation | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

In an effort to optimize the night time utilizing the exquisite weather on Maunakea, CFHT has equipped its dome with vents and is now moving its Queued Scheduled Observing (QSO)1 based operations toward Signal to Noise Ratio (SNR) observing. In this new mode, individual exposure times for a science program are estimated using a model that uses measurements of the weather conditions as input and the science program is considered completed when the depth required by the scientific requirements are reached. These changes allow CFHT to make better use of the excellent seeing conditions provided by Maunakea, allowing us to complete programs in a shorter time than allocated to the science programs. © 2016 SPIE.


Lecrevisse T.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Iwasa Y.,Massachusetts Institute of Technology
IEEE Transactions on Applied Superconductivity | Year: 2016

In this paper, we report preliminary experimental results on protection study of two REBCO pancake coils based on the metal-as-insulation (MI) winding technique, a variant of the no-insulation (NI) winding technique, in which a metallic tape is cowound. Against the more-proven NI technique, our results demonstrate that the MI technique, too, is quite viable for HTS pancake coils with the following features: 1) nearly self-protecting; 2) significantly smaller charging-delay time constant; and 3) better control of coil parameters. It also permits stable operation at 97% of a quench current. We present 77-K results of NI and MI pancakes: first, comparing the advantages and drawbacks of the two winding techniques and, second, dealing with stability and quench parameters. Finally, using a simple circuit model, we quantitatively show that metallic tape thickness has little detrimental effect on the self-protecting feature of the MI pancakes. © 2002-2011 IEEE.


Ronayette L.,CNRS French National High Magnetic Field Laboratory | Barbier R.,CNRS French National High Magnetic Field Laboratory | Bredy Ph.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Fazilleau Ph.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | And 5 more authors.
Refrigeration Science and Technology | Year: 2012

A CEA-CNRS French collaboration is currently developing a new hybrid magnet. This magnet combines a resistive insert, composed of Bitter and polyhelix coils, and a large bore superconducting coil (subsequently named "outsert" due to its outermost location), to create an overall continuous magnetic field of 43 T in a 34 mm warm bore aperture. The superconducting coil, based on the novel development of a Nb-Ti/Cu Rutherford Cable On Conduit Conductor (RCOCC) cooled down to 1.8 K by a bath of superfluid helium at atmospheric pressure, aims at producing a continuous magnetic field of 8.5 T in a 1.1 m cold bore diameter. The cryogenic requirements will be presented together with design principles and parameters.


Hervieu B.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Berriaud C.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Berthier R.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Debray F.,CNRS French National High Magnetic Field Laboratory | And 7 more authors.
Physics Procedia | Year: 2015

The association of two inner resistive coils (Polyhelix and Bitter) producing 34.5 T with an outer NbTi superconducting coil producing 8.5 T to obtain a 43 T hybrid magnet is a technical challenge. Accidental failure modes leading to complex electromagnetic behaviors and large transient dynamical forces should be anticipated. These considerations lead to a reinforced design and a thermo-hydraulic strategy to limit the overpressure. The cryostat has been designed with innovative thermo-mechanical supports sustaining the coil at 1.8 K-1200 hPa and the eddy current shield at 30 K, both being possibly overloaded by high dynamic forces in the worst accidental failure case. © 2015 The Authors.


Schussler F.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers
Proceedings of the 32nd International Cosmic Ray Conference, ICRC 2011 | Year: 2011

We present the search for the diffuse flux of astrophysical muon neutrinos using data collected by the ANTARES neutrino telescope. We introduce a novel method to estimate the energy of high-energy muons traversing the ANTARES detector and discuss detailed comparisons between data and Monte Carlo simulations. Using data recorded in 2008 and 2009 a search for a high-energy excess over the expected atmospheric neutrino background is presented and stringent limits on the diffuse flux of astrophysical muon neutrinos in the energy range 20 TeV - 2.5 PeV are derived.


Schussler F.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers
Proceedings of the 32nd International Cosmic Ray Conference, ICRC 2011 | Year: 2011

Clustering of neutrino arrival directions would provide hints for their astrophysical origin. The two-point autocorrelation method is sensitive to a large variety of cluster morphologies and, due to its independence from Monte Carlo simulations, provides complementary information to searches for the astrophysical sources of high energy muon neutrinos. We present the analysis of the autocorrelation function as a function of the angular scale of data collected during 2007-08 with the ANTARES neutrino telescope.


Vallcorba R.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Mayri C.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Gastineau B.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Maksoud W.A.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | And 7 more authors.
Physics Procedia | Year: 2015

The R3B-Glad magnet cold mass has been tested in the test facility at CEA Saclay previously used for testing W7X coils. This superconducting dipole has been cooled down by indirect cooling, and its 21 tons were maintained at around 4.8 K by means of helium thermosiphon. For this, the facility was adapted and connected to the cold mass to approximate actual conditions in its final configuration at GSI (Darmstadt, Germany). The magnet cooling down as well as the two-slope current ramping up to the nominal current of 3584 A was successfully achieved in December 2013. This paper presents the cryogenic distribution process, and shows the relevant results. © 2015 The Authors.


Chipaux R.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers | Gentit F.-X.,Institute Of Recherche Sur Les Lois Fondamentales Of Lunivers
IEEE Transactions on Nuclear Science | Year: 2010

The aging of CMS electronic calorimeter scintillating crystals under radiation leads to a deterioration of their transparency, and thus of their effective light yield and their calibration. The correlation between transparency variation, as measured by the fiber-optic monitoring system, and the calibration variation depends on the optical properties of the scintillating material itself and of its environment. In previous studies, the possibility of light scattering within the bulk of the crystals was not taken into account. We present here the results of the simulation of this correlation for different types of CMS electronic calorimeter crystals using the program Litrani improved to allow light scattering in bulk. They show that scattering could explain the variation of correlation coefficients observed between CMS/ECAL endcap and barrel crystals..

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