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Search Results: 1 - 10 of 3000 matches for " Thierry Lasserre "
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Light Sterile Neutrinos in Particle Physics: Experimental Status
Thierry Lasserre
Physics , 2014,
Abstract: Most of the neutrino oscillation results can be explained by the three-neutrino paradigm. However several anomalies in short baseline oscillation data could be interpreted by invoking a hypothetical fourth neutrino, separated from the three standard neutrinos by a squared mass difference of more than 0.1 eV$^2$. This new neutrino, often called sterile, would not feel standard model interactions but mix with the others. Such a scenario calling for new physics beyond the standard model has to be either ruled out or confirmed with new data. After a brief review of the anomalous oscillation results we discuss the world-wide experimental proposal aiming to clarify the situation.
Double Chooz, A Search for the Neutrino Mixing Angle theta-13
Maury Goodman Thierry Lasserre
Physics , 2006,
Abstract: The Double Chooz Reactor Neutrino Experiment in France plans to quickly measure the neutrino mixing angle theta-13, or limit it to sin^2 2-theta_13 less than 0.025. The physics reach, experimental site, detector structures, scintillator, photodetection, electronics, calibration and simulations are described. The possibility of using Double Chooz to explore the possible use of a antineutrino detector for non-proliferation goals is also presented.
Reactor Neutrinos
Thierry Lasserre,Henry W. Sobel
Physics , 2006, DOI: 10.1016/j.crhy.2005.08.002
Abstract: We review the status and the results of reactor neutrino experiments, that toe the cutting edge of neutrino research. Short baseline experiments have provided the measurement of the reactor neutrino spectrum, and are still searching for important phenomena such as the neutrino magnetic moment. They could open the door to the measurement of coherent neutrino scattering in a near future. Middle and long baseline oscillation experiments at Chooz and KamLAND have played a relevant role in neutrino oscillation physics in the last years. It is now widely accepted that a new middle baseline disappearance reactor neutrino experiment with multiple detectors could provide a clean measurement of the last undetermined neutrino mixing angle theta13. We conclude by opening on possible use of neutrinos for Society: NonProliferation of Nuclear materials and Geophysics.
The HLMA project: determination of high delta-m^2 LMA mixing parameters and constraint on |U_e3| with a new reactor neutrino experiment
Stefan Schoenert,Thierry Lasserre,Lothar Oberauer
Physics , 2002, DOI: 10.1016/S0927-6505(02)00181-0
Abstract: In the forthcoming months, the KamLAND experiment will probe the parameter space of the solar large mixing angle (LMA) MSW solution as the origin of the solar neutrino deficit with $\nuebar$'s from distant nuclear reactors. If however the solution realized in nature is such that $\Dm2_{sol} \gsim 2 \cdot 10^{-4}$ eV$^2$ (thereafter named the HLMA region), KamLAND will only observe a rate suppression but no spectral distortion and hence it will not have the optimal sensitivity to measure the mixing parameters. In this case, we propose a new medium baseline reactor experiment located at Heilbronn (Germany) to pin down the precise value of the solar mixing parameters. In this paper, we present the Heilbronn detector site, we calculate the $\nuebar$ interaction rate and the positron spectrum expected from the surrounding nuclear power plants. We also discuss the sensitivity of such an experiment to |U_e3| in both normal and inverted neutrino mass hierarchy scenarios. We then outline the detector design, estimate background signals induced by natural radioactivity as well as by in-situ cosmic ray muon interaction, and discuss a strategy to detect the anti-neutrino signal 'free of background'.
A unified analysis of the reactor neutrino program towards the measurement of the theta_13 mixing angle
Guillaume Mention,Thierry Lasserre,Dario Motta
Physics , 2007, DOI: 10.1088/1742-6596/110/8/082013
Abstract: We present in this article a detailed quantitative discussion of the measurement of the leptonic mixing angle theta_13 through currently scheduled reactor neutrino oscillation experiments. We thus focus on Double Chooz (Phase I & II), Daya Bay (Phase I & II) and RENO experiments. We perform a unified analysis, including systematics, backgrounds and accurate experimental setup in each case. Each identified systematic error and background impact has been assessed on experimental setups following published data when available and extrapolating from Double Chooz acquired knowledge otherwise. After reviewing the experiments, we present a new analysis of their sensitivities to sin^2(2 theta_13) and study the impact of the different systematics based on the pulls approach. Through this generic statistical analysis we discuss the advantages and drawbacks of each experimental setup.
SNIF: A Futuristic Neutrino Probe for Undeclared Nuclear Fission Reactors
Thierry Lasserre,Maximilien Fechner,Guillaume Mention,Romain Reboulleau,Michel Cribier,Alain Letourneau,David Lhuillier
Physics , 2010,
Abstract: Today reactor neutrino experiments are at the cutting edge of fundamental research in particle physics. Understanding the neutrino is far from complete, but thanks to the impressive progress in this field over the last 15 years, a few research groups are seriously considering that neutrinos could be useful for society. The International Atomic Energy Agency (IAEA) works with its Member States to promote safe, secure and peaceful nuclear technologies. In a context of international tension and nuclear renaissance, neutrino detectors could help IAEA to enforce the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). In this article we discuss a futuristic neutrino application to detect and localize an undeclared nuclear reactor from across borders. The SNIF (Secret Neutrino Interactions Finder) concept proposes to use a few hundred thousand tons neutrino detectors to unveil clandestine fission reactors. Beyond previous studies we provide estimates of all known background sources as a function of the detector's longitude, latitude and depth, and we discuss how they impact the detectability.
Prototype scintillator cell for an In-based solar neutrino detector
Dario Motta,Christian Buck,Francis Xavier Hartmann,Thierry Lasserre,Stefan Sch?nert,Ute Schwan
Physics , 2005, DOI: 10.1016/j.nima.2005.03.166
Abstract: We describe the work carried out at MPIK to design, model, build and characterize a prototype cell filled with a novel indium-loaded scintillator of interest for real-time low energy solar neutrino spectroscopy. First, light propagation in optical modules was studied with experiments and Monte Carlo simulations. Subsequently a 5 cm x 5 cm x 100 cm prototype detector was set up and the optical performances of several samples were measured. We first tested a benchmark PXE-based scintillator, which performed an attenuation length of ~ 4.2 m and a photo-electron yield of ~ 730 pe/MeV. Then we measured three In-loaded samples. At an In-loading of 44 g/l, an energy resolution of ~ 11.6 % and a spatial resolution of ~ 7 cm were attained for 477 keV recoil electrons. The long-range attenuation length in the cell was ~1.3 m and the estimated photo-electron yield ~ 200 pe/MeV. Light attenuation and relative light output of all tested samples could be reproduced reasonably well by MC. All optical properties of this system have remained stable over a period of > 1 y.
Rank-constrained fundamental matrix estimation by polynomial global optimization versus the eight-point algorithm
Florian Bugarin,Adrien Bartoli,Didier Henrion,Jean-Bernard Lasserre,Jean-José Orteu,Thierry Sentenac
Mathematics , 2014,
Abstract: The fundamental matrix can be estimated from point matches. The current gold standard is to bootstrap the eight-point algorithm and two-view projective bundle adjustment. The eight-point algorithm first computes a simple linear least squares solution by minimizing an algebraic cost and then projects the result to the closest rank-deficient matrix. We propose a single-step method that solves both steps of the eight-point algorithm. Using recent results from polynomial global optimization, our method finds the rank-deficient matrix that exactly minimizes the algebraic cost. In this special case, the optimization method is reduced to the resolution of very short sequences of convex linear problems which are computationally efficient and numerically stable. The current gold standard is known to be extremely effective but is nonetheless outperformed by our rank-constrained method for bootstrapping bundle adjustment. This is here demonstrated on simulated and standard real datasets. With our initialization, bundle adjustment consistently finds a better local minimum (achieves a lower reprojection error) and takes less iterations to converge.
A survey of primary care physician practices in antibiotic prescribing for the treatment of uncomplicated male gonoccocal urethritis
Alessandra Falchi, Andrea Lasserre, Anne Gallay, Thierry Blanchon, Patrice Sednaoui, Fran?ois Lassau, Veronique Massari, Clément Turbelin, Thomas Hanslik
BMC Family Practice , 2011, DOI: 10.1186/1471-2296-12-35
Abstract: We developed a clinical vignette describing a man with typical gonococcal urethritis symptoms to elicit questions about antibiotic treatment. We mailed the electronic questionnaire to a random sample of 1000 French GPs belonging to the Sentinelles Network.By the end of the survey period, 350 vignettes were received, yielding a response rate of 35%. Sixty-six GPs (20.2%) prescribed the recommended antibiotics for the simultaneous treatment of N. gonorrhoeae and C. trachomatis infections, while 132 GPs (40.4%) prescribed only non-recommended antibiotics, including ciprofloxacin in 69 cases (21.1%). General practitioners with less than 10 years in practice showed better compliance to guidelines than those with more years in practice (p < 0.05).The results suggest a mismatch between the guidelines and the antibiotic treatment of male uncomplicated urethritis by French GPs, mostly among the subgroup of physicians who have been in practice longer. Educational approaches based on practice feedback need to be developed to improve these deficits in the quality of care.Over the last few years, the number of gonorrhoea cases, caused by the gram negative bacterium Neisseria gonorrhoeae, has continually increased in many European countries, the United States and China [1-3]. However, over the past 60 years N. gonorrhoeae has developed resistance to multiple classes of antimicrobials. Since the first report of tetracycline resistance in 1985, gonococci that are resistant to tetracycline have spread globally [4]. During a sentinel surveillance study in Western Europe in 2004, a total of 1055 gonoccocal isolates were analysed of which 21.3% showed resistance to penicillin [5]. In addition, high levels of ciprofloxacin-resistant strains were reported worldwide in the early 1990s [6].In France, an increase in the incidence of gonorrhoea cases has been indicated since 1998 [7]. In 2006, the number of gonorrhoea cases increased by more than 50% compared to 2005. Resistance of N. gonorr
A proposed search for a fourth neutrino with a PBq antineutrino source
Michel Cribier,Maximilien Fechner,Thierry Lasserre,Alain Letourneau,David Lhuillier,Guillaume Mention,Davide Franco,Vasily Kornoukhov,Stefan Schoenert
Physics , 2011, DOI: 10.1103/PhysRevLett.107.201801
Abstract: Several observed anomalies in neutrino oscillation data can be explained by a hypothetical fourth neutrino separated from the three standard neutrinos by a squared mass difference of a few eV^2. We show that this hypothesis can be tested with a PBq (ten kilocurie scale) 144Ce or 106Ru antineutrino beta-source deployed at the center of a large low background liquid scintillator detector. In particular, the compact size of such a source could yield an energy-dependent oscillating pattern in event spatial distribution that would unabiguously determine neutrino mass differences and mixing angles.
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