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Search Results: 1 - 10 of 435733 matches for " J. G. Learned "
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A Relational Argument for a $\sim$PeV Neutrino Energy Cutoff
John G. Learned,Thomas J. Weiler
Physics , 2014,
Abstract: We present a relationship, E_\nu^{max} = m_{\nu} M_{Planck}/M_{weak}, among the highest observed neutrino energy (~PeV) and the neutrino mass, the weak scale, and the Planck energy. We then discuss some tests of this relationship, and present some theoretical constructs which motivate the relationship. It is possible that all massive particles are subject to maximum energies given by similar relationships, although only the neutrino seems able to offer interesting phenomenology. We discuss implications which include no neutrino detections at energies greater than PeV, and changes in expectations for the highest energy cosmic rays. A virtue of this hypothesis is that it is easily invalidated should neutrinos be observed with energies much great than the PeV scale. An almost inescapable implication is that Lorentz Invariance is a low energy principle, yet it appears that violation may be only observable in high-energy astrophysical neutrinos.
Neutrino Decay as an Explanation of Atmospheric Neutrino Observations
V. Barger,J. G. Learned,S. Pakvasa,T. J. Weiler
Physics , 1998, DOI: 10.1103/PhysRevLett.82.2640
Abstract: We show that the observed zenith angle dependence of the atmospheric neutrinos can be accounted for by neutrino decay. Furthermore, it is possible to account for all neutrino anomalies with just three flavors.
Underground Muons in Super-KAMIOKANDE
The Super-Kamiokande Collaboration,presented by J. G. Learned
Physics , 1997,
Abstract: The largest underground neutrino observatory, Super-Kamiokande, located near Kamioka, Japan has been collecting data since April 1996. It is located at a depth of roughly 2.7 kmwe in a zinc mine under a mountain, and has an effective area for detecting entering-stopping and through-going muons of about $1238 m^2$ for muons of $>1.7 GeV$. These events are collected at a rate of 1.5 per day from the lower hemisphere of arrival directions, with 2.5 muons per second in the downgoing direction. We report preliminary results from 229 live days analyzed so far with respect to zenith angle variation of the upcoming muons. These results do not yet have enough statistical weight to discriminate between the favored hypothesis for muon neutrino oscillations and no-oscillations. We report on the search for astrophysical sources of neutrinos and high energy neutrino fluxes from the sun and earth center, as might arise from WIMP annihilations. None are found. We also present a topographical map of the overburden made from the downgoing muons. The detector is performing well, and with several years of data we should be able to make significant progress in this area.
Up-Down Asymmetry of Neutral Current Events as a Diagnostic for Nu_mu - Nu-st Versus Nu_mu- Nu_tau Oscillations
John G. Learned,Sandip Pakvasa,J. L. Stone
Physics , 1998, DOI: 10.1016/S0370-2693(98)00806-5
Abstract: We show that the asymmetry in the neutral current events (e.g. Nu N -> Nu N pi^0) can be used to discriminate between Nu_mu - Nu_tau and Nu_mu - Nu_st mixing as being responsible for the atmospheric neutrino anomaly. Specifically, A_N vanishes for Nu_mu - Nu_tau mixing and is about 2/3 A_mu for Nu_mu - Nu_st mixing.
Hanohano:A Deep Ocean Antineutrino Observatory
Batygov, M.;Dye, S. T.;Learned, J. G.;Matsuno, S.;Pakvasa, S.;Varner, G.
High Energy Physics - Phenomenology , 2008,
Abstract: This paper presents the science potential of a deep ocean antineutrino observatory being developed at Hawaii and elsewhere. The observatory design allows for relocation from one site to another. Positioning the observaory some 60 km distant from a nuclear reactor complex enables preecision measurement of neutrino mixing parameters, leading to a determination of neutrino mass hierarchy and theta_13. At a mid-Pacific location, the observatory measures the flux of uranium and thorium decay series antineutrinos from earth's mantle and performs a sensitive search for a hypothetical natural fission reactor in earth's core. A subequent deployment at another mid-ocean location would test lateral homogeneity of uranium and thorium in earth's mantle. These measurements have significance for earth energy studies.
Hanohano:A Deep Ocean Antineutrino Observatory
M. Batygov,S. T. Dye,J. G. Learned,S. Matsuno,S. Pakvasa,G. Varner
Physics , 2008, DOI: 10.1088/1742-6596/136/4/042002
Abstract: This paper presents the science potential of a deep ocean antineutrino observatory being developed at Hawaii and elsewhere. The observatory design allows for relocation from one site to another. Positioning the observaory some 60 km distant from a nuclear reactor complex enables preecision measurement of neutrino mixing parameters, leading to a determination of neutrino mass hierarchy and theta_13. At a mid-Pacific location, the observatory measures the flux of uranium and thorium decay series antineutrinos from earth's mantle and performs a sensitive search for a hypothetical natural fission reactor in earth's core. A subequent deployment at another mid-ocean location would test lateral homogeneity of uranium and thorium in earth's mantle. These measurements have significance for earth energy studies.
Nuclear Security Applications of Antineutrino Detectors: Current Capabilities and Future Prospects
A. Bernstein,G. Baldwin,B. Boyer,M. Goodman,J. Learned,J. Lund,D. Reyna,R. Svoboda
Physics , 2009, DOI: 10.1080/08929882.2010.529785
Abstract: Antineutrinos are electrically neutral, nearly massless fundamental particles produced in large numbers in the cores of nuclear reactors and in nuclear explosions. In the half century since their discovery, major advances in the understanding of their properties, and in detector technology, have opened the door to a new discipline: Applied Antineutrino Physics. Because antineutrinos are inextricably linked to the process of nuclear fission, many applications of interest are in nuclear nonproliferation. This white paper presents a comprehensive survey of applied antineutrino physics relevant for nonproliferation, summarizes recent advances in the field, describes the overlap of this nascent discipline with other ongoing fundamental and applied antineutrino research, and charts a course for research and development for future applications. It is intended as a resource for policymakers, researchers, and the wider nuclear nonproliferation community.
Gamma--Ray Bursters, Neutrinos, and Cosmology
T. J. Weiler,W. A. Simmons,S. Pakvasa,J. G. Learned
Physics , 1994,
Abstract: Gamma ray burst (GRB) objects are now widely thought to be at cosmological distances, and thus represent enormous energy emission. Gamma ray spectra extending to $GeV$ energies suggest the possiblity of accompanying neutrino emission, and there are several models proposed suggesting the potential detectability of such coincident neutrino bursts. With this in view, we examine possible measurements that might be conducted to give experimental data useful for astronomy, for cosmology and also neutrino properties. Of interest to astronomy and cosmology, we show how measurement of neutrino flavor ratios yields information on the nature and relative distance of the source. We point out that cosmological time dilation might be measured for these sources using neutrinos, as has been done for photons, and that neutrino oscillation lengths in the range of $1$ to $10^5~Mpc$ can be probed with GRB neutrinos. We thus note that these sources may make possible the first non-electromagnetic measurements of the scale size of the universe. We discuss tests of the weak equivalence principle, tests for flavor dependent gravitational couplings, and tests for long time scale variation of physical constants. We also show that a number of new bounds on neutrino properties (charge, mass, speed, lifetime) could be facilitated to levels well beyond those already inferred from the neutrino observation of SN1987A. We also examine the implications of these physics opportunities for designers of neutrino telescopes. We conclude that detection may be possible in planned instruments if the spectra are power law extending to the $TeV$ energy region, and if the neutrino fluxes are equal to or greater than the gamma ray fluxes. We emphasize the importance of low energy detection in future experiments
Neutrino Decay and Atmospheric Neutrinos
V. Barger,J. G. Learned,P. Lipari,M. Lusignoli,S. Pakvasa,T. J. Weiler
Physics , 1999, DOI: 10.1016/S0370-2693(99)00887-4
Abstract: We reconsider neutrino decay as an explanation for atmospheric neutrino observations. We show that if the mass-difference relevant to the two mixed states \nu_\mu and \nu_\tau is very small (< 10^{-4} eV^2), then a very good fit to the observations can be obtained with decay of a component of \nu_\mu to a sterile neutrino and a Majoron. We discuss how the K2K and MINOS long-baseline experiments can distinguish the decay and oscillation scenarios.
Glashow resonance as a window into cosmic neutrino sources
V. Barger,Lingjun Fu,J. G. Learned,D. Marfatia,S. Pakvasa,T. J. Weiler
Physics , 2014, DOI: 10.1103/PhysRevD.90.121301
Abstract: The Glashow resonance at E_\nu=6.3 PeV is a measure of the \bar\nu_e content of the astrophysical neutrino flux. The fractional \bar\nu_e content depends on the neutrino production model at the cosmic neutrino source, and the environment at the source. Thus, the strength of the Glashow resonance event rate is a potential window into astrophysical sources. We quantify the "Glashow resonometer" and comment on the significance that no Glashow events are observed in the IceCube three-year data.
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