Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Prospects for Detecting Supernova Neutrino Flavor Oscillations  [PDF]
G. M. Fuller,W. C. Haxton,G. C. McLaughlin
Physics , 1998, DOI: 10.1103/PhysRevD.59.085005
Abstract: The neutrinos from a Type II supernova provide perhaps our best opportunity to probe cosmologically interesting muon and/or tauon neutrino masses. This is because matter enhanced neutrino oscillations can lead to an anomalously hot nu_e spectrum, and thus to enhanced charged current cross sections in terrestrial detectors. Two recently proposed supernova neutrino observatories, OMNIS and LAND, will detect neutrons spalled from target nuclei by neutral and charged current neutrino interactions. As this signal is not flavor specific, it is not immediately clear whether a convincing neutrino oscillation signal can be extracted from such experiments. To address this issue we examine the responses of a series of possible light and heavy mass targets, 9Be, 23Na, 35Cl, and 208Pb. We find that strategies for detecting oscillations which use only neutron count rates are problematic at best, even if cross sections are determined by ancillary experiments. Plausible uncertainties in supernova neutrino spectra tend to obscure rate enhancements due to oscillations. However, in the case of 208Pb, a signal emerges that is largely flavor specific and extraordinarily sensitive to the nu_e temperature, the emission of two neutrons. This signal and its flavor specificity are associated with the strength and location of the first-forbidden responses for neutral and charge current reactions, aspects of the 208Pb neutrino cross section that have not been discussed previously. Hadronic spin transfer experiments might be helpful in confirming some of the nuclear structure physics underlying our conclusions.
Locating Sensors for Detecting Source-to-Target Patterns of Special Nuclear Material Smuggling: A Spatial Information Theoretic Approach  [PDF]
Jay Przybyla,Jeffrey Taylor,Xuesong Zhou
Sensors , 2010, DOI: 10.3390/s100908070
Abstract: In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy.
Muon-induced neutron production and detection with GEANT4 and FLUKA  [PDF]
H. M. Araujo,V. A. Kudryavtsev,N. J. C. Spooner,T. J. Sumner
Physics , 2004, DOI: 10.1016/j.nima.2005.02.004
Abstract: We report on a comparison study of the Monte Carlo packages GEANT4 and FLUKA for simulating neutron production by muons penetrating deep underground. GEANT4 is found to generate fewer neutrons at muon energies above ~100 GeV, by at most a factor of 2 in some materials, which we attribute mainly to lower neutron production in hadronic cascades. As a practical case study, the muon-induced neutron background expected in a 250 kg liquid-xenon WIMP dark matter detector was calculated and good agreement was found for the recoil event rates. The detailed model of neutron elastic scattering in GEANT4 was also shown to influence the nuclear recoil spectrum observed in the target, which is presently a shortcoming of FLUKA. We conclude that both packages are suited for this type of simulation, although further improvements are desirable in both cases.
Universal formula for the muon-induced neutron yield  [PDF]
N. Yu. Agafonova,A. S. Malgin
Physics , 2013, DOI: 10.1103/PhysRevD.87.113013
Abstract: The experimental data on the yield of muon-induced neutrons for liquid scintillator, iron and lead accumulated during 60 years of muon interaction underground study have been analyzed. A universal formula connecting the yield with muon energy loss in the matter and neutron production in hadronic and electromagnetic showers is presented.
Muon and Cosmogenic Neutron Detection in Borexino  [PDF]
Borexino Collaboration,G. Bellini,J. Benziger,D. Bick,S. Bonetti,M. Buizza Avanzini,B. Caccianiga,L. Cadonati,F. Calaprice,C. Carraro,A. Chavarria,A. Chepurnov,D. D'Angelo,S. Davini,A. Derbin,A. Etenko,F. von Feilitzsch,K. Fomenko,D. Franco,C. Galbiati,S. Gazzana,C. Ghiano,M. Giammarchi,M. Goeger-Neff,A. Goretti,E. Guardincerri,S. Hardy,Aldo Ianni,Andrea Ianni,M. Joyce,V. Kobychev,Y. Koshio,D. Korablev,G. Korga,D. Kryn,M. Laubenstein,C. Lendvai,T. Lewke,E. Litvinovich,B. Loer,F. Lombardi,P. Lombardi,L. Ludhova,I. Machulin,S. Manecki,W. Maneschg,G. Manuzio,Q. Meindl,E. Meroni,L. Miramonti,M. Misiaszek,D. Montanari,V. Muratova,L. Oberauer,M. Obolensky,F. Ortica,M. Pallavicini,L. Papp,L. Perasso,S. Perasso,A. Pocar,R. S. Raghavan,G. Ranucci,A. Razeto,A. Re,A. Romani,D. Rountree,A. Sabelnikov,R. Saldanha,C. Salvo,S. Sch?nert,H. Simgen,M. Skorokhvatov,O. Smirnov,A. Sotnikov,S. Sukhotin,Y. Suvorov,R. Tartaglia,G. Testera,D. Vignaud,R. B. Vogelaar,J. Winter,M. Wojcik,A. Wright,M. Wurm,J. Xu,O. Zaimidoroga,S. Zavatarelli,G. Zuzel
Physics , 2011, DOI: 10.1088/1748-0221/6/05/P05005
Abstract: Borexino, a liquid scintillator detector at LNGS, is designed for the detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear reactors, and the Earth. The feeble nature of these signals requires a strong suppression of backgrounds below a few MeV. Very low intrinsic radiogenic contamination of all detector components needs to be accompanied by the efficient identification of muons and of muon-induced backgrounds. Muons produce unstable nuclei by spallation processes along their trajectory through the detector whose decays can mimic the expected signals; for isotopes with half-lives longer than a few seconds, the dead time induced by a muon-related veto becomes unacceptably long, unless its application can be restricted to a sub-volume along the muon track. Consequently, not only the identification of muons with very high efficiency but also a precise reconstruction of their tracks is of primary importance for the physics program of the experiment. The Borexino inner detector is surrounded by an outer water-Cherenkov detector that plays a fundamental role in accomplishing this task. The detector design principles and their implementation are described. The strategies adopted to identify muons are reviewed and their efficiency is evaluated. The overall muon veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction algorithms developed are presented. Their performance is tested against muon events of known direction such as those from the CNGS neutrino beam, test tracks available from a dedicated External Muon Tracker and cosmic muons whose angular distribution reflects the local overburden profile. The achieved angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending on the impact parameter of the crossing muon. The methods implemented to efficiently tag cosmogenic neutrons are also presented.
Status and Future Prospects in Searches for New Interactions in Neutron and Nuclear Beta-decay, Muon- and Pion-decay  [PDF]
Jules Deutsch
Physics , 1999,
Abstract: The interest, the status and the perspectives of various experiments in neutron and nuclear beta-decay, muon-decay and pion-decays are discussed. The talk is segmented into a discussion of the decay-rates and of the energy-spectra and correlations. The impact on various scenarios of "new physics" is briefly mentioned; left-right symmetric models are discussed in more detail and the informations gained from the considered experiments is compared to those from other sources.
Measurement of muon induced neutron background at shallow sites  [PDF]
J. Wolf
Physics , 2002,
Abstract: Cosmic muon induced neutrons are a major source of background for low countrate experiments like neutrino oscillation or dark matter searches. Especially at shallow sites these neutrons are the limiting factor for the ultimate sensitivity of the measurement. Measurements of the neutron rate and counter measures including active veto and passive shielding of the detector are discussed for two neutrino oscillation experiments at shallow sites: the KARMEN accelerator based experiment at RAL and the PALO VERDE reactor experiment.
Measuring the Cosmic Ray Muon-Induced Fast Neutron Spectrum by (n,p) Isotope Production Reactions in Underground Detectors  [PDF]
Cristiano Galbiati,John. F. Beacom
Physics , 2005, DOI: 10.1103/PhysRevC.73.049906
Abstract: While cosmic ray muons themselves are relatively easy to veto in underground detectors, their interactions with nuclei create more insidious backgrounds via: (i) the decays of long-lived isotopes produced by muon-induced spallation reactions inside the detector, (ii) spallation reactions initiated by fast muon-induced neutrons entering from outside the detector, and (iii) nuclear recoils initiated by fast muon-induced neutrons entering from outside the detector. These backgrounds, which are difficult to veto or shield against, are very important for solar, reactor, dark matter, and other underground experiments, especially as increased sensitivity is pursued. We used fluka to calculate the production rates and spectra of all prominent secondaries produced by cosmic ray muons, in particular focusing on secondary neutrons, due to their importance. Since the neutron spectrum is steeply falling, the total neutron production rate is sensitive just to the relatively soft neutrons, and not to the fast-neutron component. We show that the neutron spectrum in the range between 10 and 100 MeV can instead be probed by the (n, p)-induced isotope production rates 12C(n, p)12B and 16O(n, p)16N in oil- and water-based detectors. The result for 12B is in good agreement with the recent KamLAND measurement. Besides testing the calculation of muon secondaries, these results are also of practical importance, since 12B (T1/2 = 20.2 ms, Q = 13.4 MeV) and 16N (T1/2 = 7.13 s, Q = 10.4 MeV) are among the dominant spallation backgrounds in these detectors.
Simulations of muon-induced neutron flux at large depths underground  [PDF]
V. A. Kudryavtsev,N. J. C. Spooner,J. E. McMillan
Physics , 2003, DOI: 10.1016/S0168-9002(03)00983-5
Abstract: The production of neutrons by cosmic-ray muons at large depths underground is discussed. The most recent versions of the muon propagation code MUSIC, and particle transport code FLUKA are used to evaluate muon and neutron fluxes. The results of simulations are compared with experimental data.
Detecting Majorana nature of neutrinos in muon and tau decay
Fukuyama, Takeshi;Tsumura, Koji
High Energy Physics - Phenomenology , 2008,
Abstract: The Majorana nature of neutrinos can be detected by the precise measurement of muon decay. This possibility comes from the presence of charged Higgs boson interaction for Majorana neutrinos. We study the effects of the neutrino Yukawa interaction via charged Higgs bosons in muon decay processes such as $\mu\to e\nu\bar{\nu}$ and $\mu\to e\gamma$. The Higgs triplet model with small vacuum expectation value is of special importance whose neutrino Yukawa coupling can affect significantly muon decays. External neutrino lines in the Feynman diagrams of $\mu\to e\nu\bar{\nu}$ can be crossed because of its Majorana nature. This fact provides the interference contribution between the W boson exchange diagram and that of charged Higgs boson, which may be detectable in near future experiments.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.