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Search Results: 1 - 10 of 462013 matches for " A. Tonazzo "
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Associated production of a Z boson and a b-jet in ATLAS
S. Diglio,A. Farilla,A. Tonazzo,M. Verducci
Physics , 2007,
Abstract: The current uncertainty on the parametrization of the partonic content of the proton (PDF's) affects the potential for the discovery of new physics at LHC. The study of Z boson production in association with a b-jet can considerably reduce such uncertainty. In addition, this process represents a background both to the search for the Higgs boson and for SUSY particles. We present an update, based on the full simulation data sample produced for the Rome Physics Workshop, of a preliminary study in the case where the Z boson decays in mu+ mu-.
A new anti-neutrino detection technique based on positronium tagging with plastic scintillators
G. Consolati,D. Franco,C. Jollet,A. Meregaglia,A. Minotti,S. Perasso,A. Tonazzo
Physics , 2015, DOI: 10.1016/j.nima.2015.06.021
Abstract: The main signature for anti-neutrino detection in reactor and geo-neutrino experiments based on scintillators is provided by the space-time coincidence of positron and neutron produced in the Inverse Beta Decay reaction. Such a signature strongly suppresses backgrounds and allows for measurements performed underground with a relatively high signal-to-background ratio. In an aboveground environment, however, the twofold coincidence technique is not sufficient to efficiently reject the high background rate induced by cosmogenic events. Enhancing the positron-neutron twofold coincidence efficiency has the potential to pave the way future aboveground detectors for reactor monitoring. We propose a new detection scheme based on a threefold coincidence, between the positron ionization, the ortho-positronium (o-Ps) decay, and the neutron capture, in a sandwich detector with alternated layers of plastic scintillator and aerogel powder. We present the results of a set of dedicated measurements on the achievable light yield and on the o-Ps formation and lifetime. The efficiencies for signal detection and background rejection of a preliminary detector design are also discussed.
Measurement of ortho-Positronium Properties in Liquid Scintillators
S. Perasso,G. Consolati,D. Franco,S. Hans,C. Jollet,A. Meregaglia,A. Tonazzo,M. Yeh
Physics , 2013, DOI: 10.1088/1748-0221/9/03/C03028
Abstract: Pulse shape discrimination in liquid scintillator detectors is a well-established technique for the discrimination of heavy particles from light particles. Nonetheless, it is not efficient in the separation of electrons and positrons, as they give rise to indistinguishable scintillator responses. This inefficiency can be overtaken through the exploitation of the formation of ortho-Positronium (o-Ps), which alters the time profile of light pulses induced by positrons. We characterized the o-Ps properties in the most commonly used liquid scintillators, i.e. PC, PXE, LAB, OIL and PC + PPO. In addition, we studied the effects of scintillator doping on the o-Ps properties for dopants currently used in neutrino experiments, Gd and Nd. Further measurements for Li-loaded and Tl-loaded liquid scintillators are foreseen. We found that the o-Ps properties are suitable for enhancing the electron-positron discrimination.
Characterization of positronium properties in doped liquid scintillators
G. Consolati,D. Franco,S. Hans,C. Jollet,A. Meregaglia,S. Perasso,A. Tonazzo,M. Yeh
Physics , 2013, DOI: 10.1103/PhysRevC.88.065502
Abstract: Ortho-positronium (o-Ps) formation and decay can replace the annihilation process, when positron interacts in liquid scintillator media. The delay induced by the positronium decay represents either a potential signature for anti-neutrino detection, via inverse beta decay, or to identify and suppress positron background, as recently demonstrated by the Borexino experiment. The formation probability and decay time of o-Ps depend strongly on the surrounding material. In this paper, we characterize the o-Ps properties in liquid scintillators as function of concentrations of gadolinium, lithium, neodymium, and tellurium, dopers used by present and future neutrino experiments. In particular, gadolinium and lithium are high neutron cross section isotopes, widely used in reactor anti-neutrino experiments, while neodymium and tellurium are double beta decay emitters, employed to investigates the Majorana neutrino nature. Future neutrino experiments may profit from the performed measurements to tune the preparation of the scintillator in order to maximize the o-Ps signature, and therefore the discrimination power.
Mass hierarchy discrimination with atmospheric neutrinos in large volume ice/water Cherenkov detectors
Franco, D.;Jollet, C.;Kouchner, A.;Kulikovskiy, V.;Meregaglia, A.;Perasso, S.;Pradier, T.;Tonazzo, A.;Van Elewyck, V.
High Energy Physics - Phenomenology , 2013,
Abstract: Large mass ice/water Cherenkov experiments, optimized to detect low energy (1-20 GeV) atmospheric neutrinos, have the potential to discriminate between normal and inverted neutrino mass hierarchies. The sensitivity depends on several model and detector parameters, such as the neutrino flux profile and normalization, the Earth density profile, the oscillation parameter uncertainties, and the detector effective mass and resolution. A proper evaluation of the mass hierarchy discrimination power requires a robust statistical approach. In this work, the Toy Monte Carlo, based on an extended unbinned likelihood ratio test statistic, was used. The effect of each model and detector parameter, as well as the required detector exposure, was then studied. While uncertainties on the Earth density and atmospheric neutrino flux profiles were found to have a minor impact on the mass hierarchy discrimination, the flux normalization, as well as some of the oscillation parameter (\Delta m^2_{31}, \theta_{13}, \theta_{23}, and \delta_{CP}) uncertainties and correlations resulted critical. Finally, the minimum required detector exposure, the optimization of the low energy threshold, and the detector resolutions were also investigated.
Mass hierarchy discrimination with atmospheric neutrinos in large volume ice/water Cherenkov detectors
D. Franco,C. Jollet,A. Kouchner,V. Kulikovskiy,A. Meregaglia,S. Perasso,T. Pradier,A. Tonazzo,V. Van Elewyck
Physics , 2013, DOI: 10.1007/JHEP04(2013)008
Abstract: Large mass ice/water Cherenkov experiments, optimized to detect low energy (1-20 GeV) atmospheric neutrinos, have the potential to discriminate between normal and inverted neutrino mass hierarchies. The sensitivity depends on several model and detector parameters, such as the neutrino flux profile and normalization, the Earth density profile, the oscillation parameter uncertainties, and the detector effective mass and resolution. A proper evaluation of the mass hierarchy discrimination power requires a robust statistical approach. In this work, the Toy Monte Carlo, based on an extended unbinned likelihood ratio test statistic, was used. The effect of each model and detector parameter, as well as the required detector exposure, was then studied. While uncertainties on the Earth density and atmospheric neutrino flux profiles were found to have a minor impact on the mass hierarchy discrimination, the flux normalization, as well as some of the oscillation parameter (\Delta m^2_{31}, \theta_{13}, \theta_{23}, and \delta_{CP}) uncertainties and correlations resulted critical. Finally, the minimum required detector exposure, the optimization of the low energy threshold, and the detector resolutions were also investigated.
Study of the performance of a large scale water-Cherenkov detector (MEMPHYS)
L. Agostino,M. Buizza-Avanzini,M. Dracos,D. Duchesneau,M. Marafini,M. Mezzetto,L. Mosca,T. Patzak,A. Tonazzo,N. Vassilopoulos
Physics , 2012, DOI: 10.1088/1475-7516/2013/01/024
Abstract: MEMPHYS (MEgaton Mass PHYSics) is a proposed large-scale water Cherenkov experiment to be performed deep underground. It is dedicated to nucleon decay searches, neutrinos from supernovae, solar and atmospheric neutrinos, as well as neutrinos from a future Super-Beam or Beta-Beam to measure the CP violating phase in the leptonic sector and the mass hierarchy. A full simulation of the detector has been performed to evaluate its performance for beam physics. The results are given in terms of "Migration Matrices" of reconstructed versus true neutrino energy, taking into account all the experimental effects.
Future large-scale water-Cherenkov detector
L. Agostino,M. Buizza-Avanzini,M. Marafini,T. Patzak,A. Tonazzo,M. Dracos,N. Vassilopoulos,D. Duchesneau,M. Mezzetto,L. Mosca
Physics , 2013, DOI: 10.1103/PhysRevSTAB.16.061001
Abstract: MEMPHYS (MEgaton Mass PHYSics) is a proposed large-scale water-Cherenkov experiment to be performed deep underground. It is dedicated to nucleon decay searches and the detection of neutrinos from supernovae, solar, and atmospheric neutrinos, as well as neutrinos from a future beam to measure the CP violating phase in the leptonic sector and the mass hierarchy. This paper provides an overview of the latest studies on the expected performance of MEMPHYS in view of detailed estimates of its physics reach, mainly concerning neutrino beams.
MEMPHYS:A large scale water Cerenkov detector at Fréjus
A. de Bellefon,J. Bouchez,J. Busto,J. -E. Campagne,C. Cavata,J. Dolbeau,J. Dumarchez,P. Gorodetzky,S. Katsanevas,M. Mezzetto,L. Mosca,T. Patzak,P. Salin,A. Tonazzo,C. Volpe
Physics , 2006,
Abstract: 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 $\delta$.
Solar neutrino detection in a large volume double-phase liquid argon experiment
D. Franco,C. Giganti,P. Agnes,L. Agostino,B. Bottino,S. Davini,S. De Cecco,A. Fan,G. Fiorillo,C. Galbiati,A. M. Goretti,E. V. Hungerford,Al. Ianni,An. Ianni,C. Jollet,L. Marini,C. J. Martoff,A. Meregaglia,L. Pagani,M. Pallavicini,E. Pantic,A. Pocar,A. L. Renshaw,B. Rossi,N. Rossi,Y. Suvorov,G. Testera,A. Tonazzo,H. Wang,S. Zavatarelli
Physics , 2015,
Abstract: The direct search for dark matter WIMP particles through their interaction with nuclei at the "neutrino floor" sensitivity, where neutrino-induced coherent scattering on nuclei starts contributing to the background, requires detectors capable of collecting exposures of the order of 1~ktonne yr free of background resulting from beta and gamma decays and cosmogenic and radiogenic neutrons. The same constraints are required for precision measurements of solar neutrinos elastically scattering on electrons. Two-phase liquid argon time projection chambers (LAr TPCs) are prime candidates for the ambitious program to explore the nature of dark matter. The large target, high scintillation light yield and good spatial resolution in all three cartesian directions concurrently allows a high precision measurement of solar neutrino fluxes. We studied the cosmogenic and radiogenic backgrounds affecting solar neutrino detection in a 300 tonne (100 tonne fiducial) LAr TPC operating at LNGS depth (3,800 meters of water equivalent). Such a detector could measure the CNO neutrino rate with 5 sigma sensitivity, and significantly improve the precision of the 7Be and pep neutrino rates compared to the currently available results from the Borexino organic liquid scintillator detector. Measurements with ~2%, ~10% and ~15% precision for 7Be, pep, and CNO neutrinos, respectively, are possible.
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