1,199 research outputs found
Review of Solar Neutrino Experiments
This paper reviews the constraints on the solar neutrino mixing parameters
with data collected by the Homestake, SAGE, GALLEX, Kamiokande,
SuperKamiokande, and SNO experiments. An emphasis will be given to the global
solar neutrino analyses in terms of matter-enhanced oscillation of two active
flavors. The results to-date, including both solar model dependent and
independent measurements, indicate that electron neutrinos are changing to
other active types on route to the Earth from the Sun. The total flux of solar
neutrinos is found to be in very good agreement with solar model calculations.
Future measurements will focus on greater accuracy for mixing parameters and on
better sensitivity to low neutrino energies.Comment: Prepared for the XXI International Symposium on Lepton and Photon
Interactions at High Energies, Fermilab, USA, 11-16 August 200
Neutrino magnetic moments, flavor mixing, and the SuperKamiokande solar data
We find that magnetic neutrino-electron scattering is unaffected by
oscillations for vacuum mixing of Dirac neutrinos with only diagonal moments
and for Majorana neutrinos with two flavors. For MSW mixing, these cases again
obtain, though the effective moments can depend on the neutrino energy. Thus,
e.g., the magnetic moments measured with from a reactor and
from the Sun could be different. With minimal assumptions, we find a
new limit on using the 825-days SuperKamiokande solar neutrino
data: at 90% CL, comparable to the
existing reactor limit.Comment: 4 pages including two inline figures. New version has 825 days SK
result, some minor revisions. Accepted for Physical Review Letter
Muon Simulations for Super-Kamiokande, KamLAND and CHOOZ
Muon backgrounds at Super-Kamiokande, KamLAND and CHOOZ are calculated using
MUSIC. A modified version of the Gaisser sea level muon distribution and a
well-tested Monte Carlo integration method are introduced. Average muon energy,
flux and rate are tabulated. Plots of average energy and angular distributions
are given. Implications on muon tracker design for future experiments are
discussed.Comment: Revtex4 33 pages, 16 figures and 4 table
Geotomography with solar and supernova neutrinos
We show how by studying the Earth matter effect on oscillations of solar and
supernova neutrinos inside the Earth one can in principle reconstruct the
electron number density profile of the Earth. A direct inversion of the
oscillation problem is possible due to the existence of a very simple analytic
formula for the Earth matter effect on oscillations of solar and supernova
neutrinos. From the point of view of the Earth tomography, these oscillations
have a number of advantages over the oscillations of the accelerator or
atmospheric neutrinos, which stem from the fact that solar and supernova
neutrinos are coming to the Earth as mass eigenstates rather than flavour
eigenstates. In particular, this allows reconstruction of density profiles even
over relatively short neutrino path lengths in the Earth, and also of
asymmetric profiles. We study the requirements that future experiments must
meet to achieve a given accuracy of the tomography of the Earth.Comment: 35 pages, 7 figures; minor textual changes in section
Supernova pointing with low- and high-energy neutrino detectors
A future galactic SN can be located several hours before the optical
explosion through the MeV-neutrino burst, exploiting the directionality of
--scattering in a water Cherenkov detector such as Super-Kamiokande. We
study the statistical efficiency of different methods for extracting the SN
direction and identify a simple approach that is nearly optimal, yet
independent of the exact SN neutrino spectra. We use this method to quantify
the increase in the pointing accuracy by the addition of gadolinium to water,
which tags neutrons from the inverse beta decay background. We also study the
dependence of the pointing accuracy on neutrino mixing scenarios and initial
spectra. We find that in the ``worst case'' scenario the pointing accuracy is
at 95% C.L. in the absence of tagging, which improves to
with a tagging efficiency of 95%. At a megaton detector, this accuracy can be
as good as . A TeV-neutrino burst is also expected to be emitted
contemporaneously with the SN optical explosion, which may locate the SN to
within a few tenths of a degree at a future km high-energy neutrino
telescope. If the SN is not seen in the electromagnetic spectrum, locating it
in the sky through neutrinos is crucial for identifying the Earth matter
effects on SN neutrino oscillations.Comment: 13 pages, 7 figures, Revtex4 format. The final version to be
published in Phys. Rev. D. A few points in the original text are clarifie
Neutrino oscillations in magnetically driven supernova explosions
We investigate neutrino oscillations from core-collapse supernovae that
produce magnetohydrodynamic (MHD) explosions. By calculating numerically the
flavor conversion of neutrinos in the highly non-spherical envelope, we study
how the explosion anisotropy has impacts on the emergent neutrino spectra
through the Mikheyev-Smirnov-Wolfenstein effect. In the case of the inverted
mass hierarchy with a relatively large theta_(13), we show that survival
probabilities of electron type neutrinos and antineutrinos seen from the
rotational axis of the MHD supernovae (i.e., polar direction), can be
significantly different from those along the equatorial direction. The event
numbers of electron type antineutrinos observed from the polar direction are
predicted to show steepest decrease, reflecting the passage of the
magneto-driven shock to the so-called high-resonance regions. Furthermore we
point out that such a shock effect, depending on the original neutrino spectra,
appears also for the low-resonance regions, which leads to a noticeable
decrease in the electron type neutrino signals. This reflects a unique nature
of the magnetic explosion featuring a very early shock-arrival to the resonance
regions, which is in sharp contrast to the neutrino-driven delayed supernova
models. Our results suggest that the two features in the electron type
antineutrinos and neutrinos signals, if visible to the Super-Kamiokande for a
Galactic supernova, could mark an observational signature of the magnetically
driven explosions, presumably linked to the formation of magnetars and/or
long-duration gamma-ray bursts.Comment: 25 pages, 21 figures, JCAP in pres
Testing Matter Effects in Very Long Baseline Neutrino Oscillation Experiments
Assuming three-neutrino mixing, we study the capabilities of very long
baseline neutrino oscillation experiments to verify and test the MSW effect and
to measure the lepton mixing angle theta_13. We suppose that intense neutrino
and antineutrino beams will become available in so-called neutrino factories.
We find that the most promising and statistically significant results can be
obtained by studying nu_e ->nu_mu and \bar{nu}_e-> \bar{nu}_mu oscillations
which lead to matter enhancements and suppressions of wrong sign muon rates. We
show the theta_13 ranges where matter effects could be observed as a function
of the baseline. We discuss the scaling laws of rates, significances and
sensitivities with the relevant mixing angles and experimental parameters. Our
analysis includes fluxes, event rates and statistical aspects so that the
conclusions should be useful for the planning of experimental setups. We
discuss the subleading Delta m^2_{21} effects in the case of the LMA MSW
solution of the solar problem, showing that they are small for L >= 7000 km.
For shorter baselines, Delta m^2_{21} effects can be relevant and their
dependence on L offers a further handle for the determination of the
CP-violation phase \delta. Finally we comment on the possibility to measure the
specific distortion of the energy spectrum due to the MSW effect.Comment: 30 pages, 13 figures, figures and more discussion added, results and
conclusions unchange
Large Extra Dimensions, Sterile neutrinos and Solar Neutrino Data
Solar, atmospheric and LSND neutrino oscillation results require a light
sterile neutrino, , which can exist in the bulk of extra dimensions.
Solar , confined to the brane, can oscillate in the vacuum to the zero
mode of and via successive MSW transitions to Kaluza-Klein states of
. This new way to fit solar data is provided by both low and
intermediate string scale models. From average rates seen in the three types of
solar experiments, the Super-Kamiokande spectrum is predicted with 73%
probability, but dips characteristic of the 0.06 mm extra dimension should be
seen in the SNO spectrum.Comment: 4 pages, 2 figure
Solar and atmospheric neutrino oscillations with three flavours
We analyze the solar and the atmospheric neutrino problems in the context of
three flavour neutrino oscillations. We assume a mass hierarchy in the vacuum
mass eigenvalues , but make no approximation
regarding the magnitudes of the mixing angles. We find that there are small but
continuous bands in the parameter space where the constraints imposed by the
current measurements of , and Kamiokande
experiments are satisfied at level. The allowed parameter space
increases dramatically if the error bars are enlarged to . The
electron neutrino survival probability has different energy dependence in
different regions of the parameter space. Measurement of the recoil electron
energy spectrum in detectors that use scattering may distinguish
between some of the allowed regions of parameter space. Finally we use the
results for the parameter space admitted by the solar neutrinos as an input for
the atmospheric neutrino problem and show that there exists a substantial
region of parameter space in which both problems can be solved.Comment: 25 pages plus eight figures. Uses Revtex. Postcript files for figures
sent separately as a uuencoded fil
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