1,040 research outputs found
Solar neutrino measurements in Super-Kamiokande-I
The details of Super--Kamiokande--I's solar neutrino analysis are given.
Solar neutrino measurement in Super--Kamiokande is a high statistics collection
of B solar neutrinos via neutrino-electron scattering. The analysis method
and results of the 1496 day data sample are presented. The final oscillation
results for the data are also presented.Comment: 32pages, 57figures, submitted to Physical Review
Experimental study of the atmospheric neutrino backgrounds for proton decay to positron and neutral pion searches in water Cherenkov detectors
The atmospheric neutrino background for proton decay to positron and neutral
pion in ring imaging water Cherenkov detectors is studied with an artificial
accelerator neutrino beam for the first time. In total, about 314,000 neutrino
events corresponding to about 10 megaton-years of atmospheric neutrino
interactions were collected by a 1,000 ton water Cherenkov detector (KT). The
KT charged-current single neutral pion production data are well reproduced by
simulation programs of neutrino and secondary hadronic interactions used in the
Super-Kamiokande (SK) proton decay search. The obtained proton to positron and
neutral pion background rate by the KT data for SK from the atmospheric
neutrinos whose energies are below 3 GeV is about two per megaton-year. This
result is also relevant to possible future, megaton-scale water Cherenkov
detectors.Comment: 13 pages, 16 figure
Search for coherent charged pion production in neutrino-carbon interactions
We report the result from a search for charged-current coherent pion
production induced by muon neutrinos with a mean energy of 1.3 GeV. The data
are collected with a fully active scintillator detector in the K2K
long-baseline neutrino oscillation experiment. No evidence for coherent pion
production is observed and an upper limit of is set on
the cross section ratio of coherent pion production to the total
charged-current interaction at 90% confidence level. This is the first
experimental limit for coherent charged pion production in the energy region of
a few GeV.Comment: 5 pages, 4 figure
Three flavor neutrino oscillation analysis of atmospheric neutrinos in Super-Kamiokande
We report on the results of a three-flavor oscillation analysis using
Super-Kamiokande~I atmospheric neutrino data, with the assumption of one mass
scale dominance (0). No significant flux change due to
matter effect, which occurs when neutrinos propagate inside the Earth for
0, has been seen either in a multi-GeV -rich sample
or in a -rich sample. Both normal and inverted mass hierarchy
hypotheses are tested and both are consistent with observation. Using
Super-Kamiokande data only, 2-dimensional 90 % confidence allowed regions are
obtained: mixing angles are constrained to and for the normal mass hierarchy. Weaker constraints,
and , are obtained
for the inverted mass hierarchy case.Comment: 7 figures, 3 table
Search for Matter-Dependent Atmospheric Neutrino Oscillations in Super-Kamiokande
We consider muon neutrino to tau neutrino oscillations in the context of the
Mass Varying Neutrino (MaVaN) model, where the neutrino mass can vary depending
on the electron density along the flight path of the neutrino. Our analysis
assumes a mechanism with dependence only upon the electron density, hence
ordinary matter density, of the medium through which the neutrino travels.
Fully-contained, partially-contained and upward-going muon atmospheric neutrino
data from the Super--Kamiokande detector, taken from the entire SK--I period of
1489 live days, are compared to MaVaN model predictions. We find that, for the
case of 2-flavor oscillations, and for the specific models tested, oscillation
independent of electron density is favored over density dependence. Assuming
maximal mixing, the best-fit case and the density-independent case do not
differ significantly.Comment: 6 pages, 1 figur
A Measurement of Atmospheric Neutrino Flux Consistent with Tau Neutrino Appearance
A search for the appearance of tau neutrinos from \mutau oscillations in the
atmospheric neutrinos has been performed using 1489.2 days of atmospheric
neutrino data from the Super-Kamiokande-I experiment. A best fit tau neutrino
appearance signal of 138 48 (stat.) (sys.) events is
obtained with an expectation of 78 26 (sys.). The hypothesis of no tau
neutrino appearance is disfavored by 2.4 sigma.Comment: 5 pages, 3 figures, 3 tables, submitted to PR
Evidence for an oscillatory signature in atmospheric neutrino oscillation
Muon neutrino disappearance probability as a function of neutrino flight
length L over neutrino energy E was studied. A dip in the L/E distribution was
observed in the data, as predicted from the sinusoidal flavor transition
probability of neutrino oscillation. The observed L/E distribution constrained
nu_mu nu_tau neutrino oscillation parameters; 1.9x10^-3 < Delta m^2 <
3.0x10^-3 eV^2 and \sin^2(2theta) > 0.90 at 90% confidence level.Comment: 5 pages, 5 figures, submitted to PR
Solar neutrino measurements in Super-Kamiokande-II
The results of the second phase of the Super-Kamiokande solar neutrino
measurement are presented and compared to the first phase. The solar neutrino
flux spectrum and time-variation as well as oscillation results are
statistically consistent with the first phase and do not show spectral
distortion. The time-dependent flux measurement of the combined first and
second phases coincides with the full period of solar cycle 23 and shows no
correlation with solar activity. The measured boron 8 total flux is 2.38
+/-0.05(stat.) +0.16-0.15(sys.) X 10^6 cm^-2 sec^-1 and the day-night
difference is found to be -6.3 +/-4.2(stat.) +/-3.7(sys.) %. There is no
evidence of systematic tendencies between the first and second phases
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