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Search Results: 1 - 10 of 189846 matches for " G. Mention "
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The Reactor Antineutrino Anomaly
G. Mention,M. Fechner,Th. Lasserre,Th. A. Mueller,D. Lhuillier,M. Cribier,A. Letourneau
Physics , 2011, DOI: 10.1103/PhysRevD.83.073006
Abstract: Recently new reactor antineutrino spectra have been provided for 235U, 239Pu, 241Pu and 238U, increasing the mean flux by about 3 percent. To good approximation, this reevaluation applies to all reactor neutrino experiments. The synthesis of published experiments at reactor-detector distances <100 m leads to a ratio of observed event rate to predicted rate of 0.976(0.024). With our new flux evaluation, this ratio shifts to 0.943(0.023), leading to a deviation from unity at 98.6% C.L. which we call the reactor antineutrino anomaly. The compatibility of our results with the existence of a fourth non-standard neutrino state driving neutrino oscillations at short distances is discussed. The combined analysis of reactor data, gallium solar neutrino calibration experiments, and MiniBooNE-neutrino data disfavors the no-oscillation hypothesis at 99.8% C.L. The oscillation parameters are such that |Delta m_{new}^2|>1.5 eV^2 (95%) and sin^2(2\theta_{new})=0.14(0.08) (95%). Constraints on the theta13 neutrino mixing angle are revised.
Experimental Parameters for a Cerium 144 Based Intense Electron Antineutrino Generator Experiment at Very Short Baselines
J. Gaffiot,T. Lasserre,G. Mention,M. Vivier,M. Cribier,M. Durero,V. Fischer,A. Letourneau,E. Dumonteil,I. S. Saldikov,G. V. Tikhomirov
Physics , 2014, DOI: 10.1103/PhysRevD.91.072005
Abstract: The standard three-neutrino oscillation paradigm, associated with small squared mass splittings $\ll 0.1\ \mathrm{eV^2}$, has been successfully built up over the last 15 years using solar, atmospheric, long baseline accelerator and reactor neutrino experiments. However, this well-established picture might suffer from anomalous results reported at very short baselines in some of these experiments. If not experimental artifacts, such results could possibly be interpreted as the existence of at least an additional fourth sterile neutrino species, mixing with the known active flavors with an associated mass splitting $\ll 0.1\ \mathrm{eV^2}$, and being insensitive to standard weak interactions. Precision measurements at very short baselines (5 to 15 m) with intense MeV electronic antineutrino emitters can be used to probe these anomalies. In this article, the expected antineutrino signal and backgrounds of a generic experiment which consists of deploying an intense beta minus radioactive source inside or in the vicinity of a large liquid scintillator detector are studied. The technical challenges to perform such an experiment are identified, along with quantifying the possible source and detector induced systematics, and their impact on the sensitivity to the observation of neutrino oscillations at short baselines.
Prompt directional detection of galactic supernova by combining large liquid scintillator neutrino detectors
V. Fischer,T. Chirac,T. Lasserre,C. Volpe,M. Cribier,M. Durero,J. Gaffiot,T. Houdy,A. Letourneau,G. Mention,M. Pequignot,V. Sibille,M. Vivier
Physics , 2015, DOI: 10.1088/1475-7516/2015/08/032
Abstract: Core-collapse supernovae produce an intense burst of electron antineutrinos in the few-tens-of-MeV range. Several Large Liquid Scintillator-based Detectors (LLSD) are currently operated worldwide, being very effective for low energy antineutrino detection through the Inverse Beta Decay (IBD) process. In this article, we develop a procedure for the prompt extraction of the supernova location by revisiting the details of IBD kinematics over the broad energy range of supernova neutrinos. Combining all current scintillator-based detector, we show that one can locate a canonical supernova at 10 kpc with an accuracy of 45 degrees (68% C.L.). After the addition of the next generation of scintillator-based detectors, the accuracy could reach 12 degrees (68% C.L.), therefore reaching the performances of the large water Cerenkov neutrino detectors. We also discuss a possible improvement of the SuperNova Early Warning System (SNEWS) inter-experiment network with the implementation of a directionality information in each experiment. Finally, we discuss the possibility to constrain the neutrino energy spectrum as well as the mass of the newly born neutron star with the LLSD data
A large HPGe detector for the non-destructive radioassay of an ultra-low-background counting facility
M. Fechner,C. Henson,J. Gaffiot,T. Lasserre,A. Letourneau,D. Lhuillier,G. Mention,Th. A. Mueller,R. Quéval,R. Svoboda
Physics , 2011,
Abstract: We present the use of a low background counting facility, equipped with a p-type 80% relative efficiency HPGe detector, protected by active and passive shielding, and large enough to count a 10" photo-multiplier tube (PMT). A GEANT4 Monte-Carlo of this detector was developed and tuned to 3% accuracy. We report the U, Th, and K contents in three different types of PMTs used in current neutrino experiments, with accuracies of $\sim 10$ ppb for U and Th and of $\sim 15$ ppm for K.
Improved Predictions of Reactor Antineutrino Spectra
Th. A. Mueller,D. Lhuillier,M. Fallot,A. Letourneau,S. Cormon,M. Fechner,L. Giot,T. Lasserre,J. Martino,G. Mention,A. Porta,F. Yermia
Physics , 2011, DOI: 10.1103/PhysRevC.83.054615
Abstract: We report new calculations of reactor antineutrino spectra including the latest information from nuclear databases and a detailed error budget. The first part of this work is the so-called ab initio approach where the total antineutrino spectrum is built from the sum of all beta-branches of all fission products predicted by an evolution code. Systematic effects and missing information in nuclear databases lead to final relative uncertainties in the 10 to 20% range. A prediction of the antineutrino spectrum associated with the fission of 238U is given based on this ab initio method. For the dominant isotopes 235U and 239Pu, we developed a more accurate approach combining information from nuclear databases and reference electron spectra associated with the fission of 235U, 239Pu and 241Pu, measured at ILL in the 80's. We show how the anchor point of the measured total beta-spectra can be used to suppress the uncertainty in nuclear databases while taking advantage of all the information they contain. We provide new reference antineutrino spectra for 235U, 239Pu and 241Pu isotopes in the 2-8 MeV range. While the shapes of the spectra and their uncertainties are comparable to that of the previous analysis of the ILL data, the normalization is shifted by about +3% on average. In the perspective of the re-analysis of past experiments and direct use of these results by upcoming oscillation experiments, we discuss the various sources of errors and their correlations as well as the corrections induced by off equilibrium effects.
Design of a Performance Measurement System in a RTO
Slim Turki,Anne-Laure Mention
Communications of the IBIMA , 2010,
Abstract: Research and Technology Organizations (RTOs) are knowledge-intensive firms. They tend to rely mainly on their employees and their individual competencies (codified or non-codified), the networks and communities they are involved in as well as the structural resources of the organization itself. These resources, mainly of intangible nature, are expected to play an important role on the innovation capabilities of RTOs, but tend to be neglected in the traditional performance reporting and management systems. The main motivation for this research is to foster the introduction of an intangible measurement system in the RTO under investigation. This paper illustrates the application of an innovative approach, for the design of a performance measurement system in a RTO. The process of collection and reporting of intangible indicators is defined and validated by relying on an in-house approach and related tool, called EFFICENT.
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.
Hypoglycaemia related to inherited metabolic diseases in adults
Claire Douillard, Karine Mention, Dries Dobbelaere, Jean-Louis Wemeau, Jean-Marie Saudubray, Marie-Christine Vantyghem
Orphanet Journal of Rare Diseases , 2012, DOI: 10.1186/1750-1172-7-26
Endocrine manifestations related to inherited metabolic diseases in adults
Marie-Christine Vantyghem, Dries Dobbelaere, Karine Mention, Jean-Louis Wemeau, Jean-Marie Saudubray, Claire Douillard
Orphanet Journal of Rare Diseases , 2012, DOI: 10.1186/1750-1172-7-11
Abstract: Inborn errors of metabolism (IEM) are rare genetic diseases, which usually have a recessive mode of inheritance. They are classified into 3 main groups according to their mechanisms: cellular intoxication, energy deficiency, and degradation or synthesis defects of complex molecules [1]. This is a new and growing field in adulthood and is not yet very well known.Endocrine manifestations can be a complication of a previously diagnosed IEM. More rarely they may signal the presence of a new IEM, mostly those involving glucose metabolism and presenting with hypoglycaemia (see the related article for review). Nevertheless all types of endocrine disorders have been described in IEM (Table 1), and the endocrinologist should be aware of them when an endocrine disorder is associated with multisystem involvement, for example with neurological, muscular and/or hepatic features.Many endocrine manifestations in IEM might go unrecognized, especially with regard to subclinical dysfunctions. Otherwise, the long-term consequences of IEM on growth, bone metabolism and fertility have not been prospectively investigated.When fertility is maintained, all pregnancies in patients with a previously diagnosed IEM should be carefully planned and monitored, especially those with dietary management, such as with phenylketonuria. Preconception screening for hormone deficiency, especially hypothyroidism, is recommended in most IEM, as is investigation for gestational diabetes. Genetic counseling should be provided, even though most IEMs, except for mitochondrial diseases, are inherited in an autosomal recessive manner. Prenatal testing for high-risk pregnancies may be discussed if the disease-causing mutations in the family are known.The aim of this review is to identify the main IEMs in adults that can be revealed or complicated by an endocrine disorder other than hypoglycaemia.Hormones play an essential role in the coordination of complex functions such as growth, reproduction, metabolism and e
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