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Search Results: 1 - 10 of 189849 matches for " G. Consolati "
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Positronium signature in organic liquid scintillators for neutrino experiments
D. Franco,G. Consolati,D. Trezzi
Physics , 2010, DOI: 10.1103/PhysRevC.83.015504
Abstract: Electron anti-neutrinos are commonly detected in liquid scintillator experiments via inverse beta decay, by looking at the coincidence between the reaction products, neutron and positron. Prior to positron annihilation, an electron-positron pair may form an orthopositronium (o-Ps) state, with a mean life of a few ns. Even if the o-Ps decay is speeded up by spin flip or pick off effects, it may introduce distortions in the photon emission time distribution, crucial for position reconstruction and pulse shape discrimination algorithms in anti-neutrino experiments. Reversing the problem, the o-Ps induced time distortion represents a new signature for tagging anti-neutrinos in liquid scintillator. In this paper, we report the results of measurements of the o-Ps formation probability and lifetime, for the most used solvents for organic liquid scintillators in neutrino physics (pseudocumene, linear alkyl benzene, phenylxylylethane, and dodecane). We characterize also a mixture of pseudocumene +1.5 g/l of 2,5-diphenyloxazole, a fluor acting as wavelength shifter. In the second part of the paper, we demonstrate that the o-Ps induced distortion of the scintillation photon emission time distributions represent an optimal signature for tagging positrons on an event by event basis, potentially enhancing the anti-neutrino detection.
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.
Evolution of chemical-physical parameters and rheological characteristics of Sarda and Maltese goat dry hams
Rina Mazzette,Domenico Meloni,Rita Melillo,Simonetta Gianna Consolati
Italian Journal of Food Safety , 2012, DOI: 10.4081/ijfs.2012.5.17
Abstract: In Sardinia, goat farming is a very important resource. Sarda and Maltese breed are reared mainly for milk production and for suckling kids meat, while meat from adult goats is undervalued. The use of adult goat meat to obtain ripened ham will contribute to safeguard the Sardinian goat supply chain. The aim of the present study was to characterize Sarda and Maltese goat dry ham in order to evaluate the quality of autochthonous goat breed meat. Chemical-physical characteristics were determined dur-ing the production stages, while the rheological and colour parameters and the composition of the goat ham were determined at the end of ripening. The pH evolution during processing were similar to other cured meat products, e.g. sheep hams, even though the values were high, especially in the products from Sarda breed. The aw value regularly decreased during processing. Colour parameters (L*, a*, b*) in the hams from Maltese goat breed were significantly (P<0.05) higher than in those from Sarda. The Sarda goat ham showed a significantly lower percentage of moisture (42% vs 52%), an higher protein content (44.35% vs 34.19%), while no differences were pointed out in the total fat content. Among the ham rheological properties, hardness parameters showed higher levels (13850.22±7589.92 vs 11073.99±6481.31, respectively in Sarda and Maltese hams) in comparison to similar products from pork and sheep, while adhesiveness value was lower. The results show that the quality parameters of goat ripened hams are affected mainly by the charac-teristics of the goat meat, in relation on the breed and the breeding system, and, less, by the traditional technology.
Formation Of A Cold Antihydrogen Beam in AEGIS For Gravity Measurements
G. Testera,A. S. Belov,G. Bonomi,I. Boscolo,N. Brambilla,R. S. Brusa,V. M. Byakov,L. Cabaret,C. Canali,C. Carraro,F. Castelli,S. Cialdi,M. de Combarieu,D. Comparat,G. Consolati,N. Djourelov,M. Doser,G. Drobychev,A. Dupasquier,D. Fabris,R. Ferragut,G. Ferrari,A. Fischer,A. Fontana,P. Forget,L. Formaro,M. Lunardon,A. Gervasini,M. G. Giammarchi,S. N. Gninenko,G. Gribakin,R. Heyne,S. D. Hogan,A. Kellerbauer,D. Krasnicky,V. Lagomarsino,G. Manuzio,S. Mariazzi,V. A. Matveev,F. Merkt,S. Moretto,C. Morhard,G. Nebbia,P. Nedelec,M. K. Oberthaler,P. Pari,V. Petracek,M. Prevedelli,I. Y. Al-Qaradawi,F. Quasso,O. Rohne,S. Pesente,A. Rotondi,S. Stapnes,D. Sillou,S. V. Stepanov,H. H. Stroke,G. Tino,A. Vairo,G. Viesti,H. Walters,U. Warring,S. Zavatarelli,A. Zenoni,D. S. Zvezhinskij,for the AEGIS Proto-Collaboration
Physics , 2008, DOI: 10.1063/1.2977857
Abstract: The formation of the antihydrogen beam in the AEGIS experiment through the use of inhomogeneous electric fields is discussed and simulation results including the geometry of the apparatus and realistic hypothesis about the antihydrogen initial conditions are shown. The resulting velocity distribution matches the requirements of the gravity experiment. In particular it is shown that the inhomogeneous electric fields provide radial cooling of the beam during the acceleration.
Annihilation of low energy antiprotons in silicon
S. Aghion,O. Ahlén,A. S. Belov,G. Bonomi,P. Br?unig,J. Bremer,R. S. Brusa,G. Burghart,L. Cabaret,M. Caccia,C. Canali,R. Caravita,F. Castelli,G. Cerchiari,S. Cialdi,D. Comparat,G. Consolati,J. H. Derking,S. Di Domizio,L. Di Noto,M. Doser,A. Dudarev,R. Ferragut,A. Fontana,P. Genova,M. Giammarchi,A. Gligorova,S. N. Gninenko,S. Haider,J. Harasimowicz,T. Huse,E. Jordan,L. V. J?rgensen,T. Kaltenbacher,A. Kellerbauer,A. Knecht,D. Krasnicky,V. Lagomarsino,A. Magnani,S. Mariazzi,V. A. Matveev,F. Moia,G. Nebbia,P. Nédélec,N. Pacifico,V. Petrácek,F. Prelz,M. Prevedelli,C. Regenfus,C. Riccardi,O. R?hne,A. Rotondi,H. Sandaker,A. Sosa,M. A. Subieta Vasquez,M. ?pacek,G. Testera,C. P. Welsch,S. Zavatarelli
Physics , 2013,
Abstract: The goal of the AE$\mathrm{\bar{g}}$IS experiment at the Antiproton Decelerator (AD) at CERN, is to measure directly the Earth's gravitational acceleration on antimatter. To achieve this goal, the AE$\mathrm{\bar{g}}$IS collaboration will produce a pulsed, cold (100 mK) antihydrogen beam with a velocity of a few 100 m/s and measure the magnitude of the vertical deflection of the beam from a straight path. The final position of the falling antihydrogen will be detected by a position sensitive detector. This detector will consist of an active silicon part, where the annihilations take place, followed by an emulsion part. Together, they allow to achieve 1$%$ precision on the measurement of $\bar{g}$ with about 600 reconstructed and time tagged annihilations. We present here, to the best of our knowledge, the first direct measurement of antiproton annihilation in a segmented silicon sensor, the first step towards designing a position sensitive silicon detector for the AE$\mathrm{\bar{g}}$IS experiment. We also present a first comparison with Monte Carlo simulations (GEANT4) for antiproton energies below 5 MeV
Prospects for measuring the gravitational free-fall of antihydrogen with emulsion detectors
AEgIS Collaboration,S. Aghion,O. Ahlén,C. Amsler,A. Ariga,T. Ariga,A. S. Belov,G. Bonomi,P. Br?unig,J. Bremer,R. S. Brusa,L. Cabaret,C. Canali,R. Caravita,F. Castelli,G. Cerchiari,S. Cialdi,D. Comparat,G. Consolati,J. H. Derking,S. Di Domizio,L. Di Noto,M. Doser,A. Dudarev,A. Ereditato,R. Ferragut,A. Fontana,P. Genova,M. Giammarchi,A. Gligorova,S. N. Gninenko,S. Haider,J. Harasimovicz,S. D. Hogan,T. Huse,E. Jordan,L. V. J?rgensen,T. Kaltenbacher,J. Kawada,A. Kellerbauer,M. Kimura,A. Knecht,D. Krasnicky,V. Lagomarsino,A. Magnani,S. Mariazzi,V. A. Matveev,F. Moia,G. Nebbia,P. Nédélec,M. K. Oberthaler,N. Pacifico,V. Petrácek,C. Pistillo,F. Prelz,M. Prevedelli,C. Regenfus,C. Riccardi,O. R?hne,A. Rotondi,H. Sandaker,P. Scampoli,A. Sosa,J. Storey,M. A. Subieta Vasquez,M. Spacek,G. Testera,D. Trezzi,R. Vaccarone,C. P. Welsch,S. Zavatarelli
Physics , 2013, DOI: 10.1088/1748-0221/8/08/P08013
Abstract: The main goal of the AEgIS experiment at CERN is to test the weak equivalence principle for antimatter. AEgIS will measure the free-fall of an antihydrogen beam traversing a moir\'e deflectometer. The goal is to determine the gravitational acceleration g for antihydrogen with an initial relative accuracy of 1% by using an emulsion detector combined with a silicon micro-strip detector to measure the time of flight. Nuclear emulsions can measure the annihilation vertex of antihydrogen atoms with a precision of about 1 - 2 microns r.m.s. We present here results for emulsion detectors operated in vacuum using low energy antiprotons from the CERN antiproton decelerator. We compare with Monte Carlo simulations, and discuss the impact on the AEgIS project.
A Characterization of the Members of a Subfamily of Power Series Distributions  [PDF]
G. Nanjundan
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.26099
Abstract: This paper discusses a characterization of the members of a subfamily of power series distributions when their probability generating functions satisfy the functional equation where a, b and c are constants and is the derivative of f.
Double Negative Left-Handed Metamaterials for Miniaturization of Rectangular Microstrip Antenna  [PDF]
G. Singh
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.26044
Abstract: In this paper, I have explored a significant concept for the miniaturization of microstrip patch antenna configuration by using the double negative (DNG) left-handed Metamaterials, which have dielectric permittivity and magnetic permeability both negative, simultaneously. It is achieved through the concept of phase-compensation by thin slab consist of the double positive (DPS) material, which have dielectric permittivity and magnetic permeability both positive, simultaneously and DNG metamaterials as a substrate of the microstrip patch antenna. By combining the DNG metamaterial slab with the slab made of DPS materials form a cavity resonator whose dispersion relation is independent of the sum of thickness of the slabs filling this cavity but it depends on the ratio of their thicknesses. This cavity constitutes by DPS and DNG material is used as substrate of the microstrip antennas and the DNG material slab is behave as phase compensator.
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