2,644 research outputs found
How many sigmas is the solar neutrino effect?
The minimal standard electroweak model can be tested by allowing all the
solar neutrino fluxes, with undistorted energy spectra, to be free parameters
in fitting the measured solar neutrino event rates, subject only to the
condition that the total observed luminosity of the sun is produced by nuclear
fusion. The rates of the five experiments prior to SNO (chlorine, Kamiokande,
SAGE, GALLEX, Super-Kamiokande) cannot be fit by an arbitrary choice of
undistorted neutrino fluxes at the level of 2.5 sigma (formally 99% C.L.).
Considering just SNO and Super-Kamiokande, the discrepancy is at the 3.3 sigma
level(10^{-3} C.L.). If all six experiments are fit simultaneously, the formal
discrepancy increases to 4 sigma (7*10^{-5} C.L.). If the relative scaling in
temperature of the nuclear reactions that produce 7Be and 8B neutrinos is taken
into account, the formal discrepancy is at the 7.4 sigma level.Comment: 1 figure; related information at http://www.sns.ias.edu/~jn
Probability of a Solution to the Solar Neutrino Problem Within the Minimal Standard Model
Tests, independent of any solar model, can be made of whether solar neutrino
experiments are consistent with the minimal Standard Model (stable, massless
neutrinos). If the experimental uncertainties are correctly estimated and the
sun is generating energy by light-element fusion in quasi-static equilibrium,
the probability of a standard-physics solution is less than 2%. Even when the
luminosity constraint is abandoned, the probability is not more than 4%. The
sensitivity of the conclusions to input parameters is explored.Comment: PRL, Revtex, 1 figure, 5 page
Non-resonant nuclear reactions at stellar temperatures
Procedure for calculating rates of non-resonant nuclear reactions at stellar temperature
Is it possible to determine the S-factor of the hep process from a laboratory experiment?
We discuss the problem of solar hep neutrinos originating from the reaction p
+ 3He -> 4He + e+ + nu and obtain a relation between the astrophysical S-factor
of the hep process and the cross section of the process e- + 4He -> 3H + n + nu
near threshold. The relation is based on the isotopic invariance of strong
interactions.
The measurement of the latter cross section would allow to obtain
experimental information on S(hep), the value of which, at the moment, is known
only from theoretical calculations.Comment: 10 pages, no figure
Do Solar Neutrino Experiments Imply New Physics?
None of the 1000 solar models in a full Monte Carlo simulation is consistent
with the results of the chlorine or the Kamiokande experiments. Even if the
solar models are forced artifically to have a \b8 neutrino flux in agreeement
with the Kamiokande experiment, none of the fudged models agrees with the
chlorine observations. The GALLEX and SAGE experiments, which currently have
large statistical uncertainties, differ from the predictions of the standard
solar model by and , respectively.Comment: 7 pages (figures not included), Institute for Advanced Study number
AST 92/51. For a hard copy with the figures, write: [email protected]
Astrophysical neutrinos: 20th Century and Beyond
I summarize the first four decades of solar neutrino research and suggest
what may be possible to learn with extragalactic neutrinos and with solar
neutrinos in the next decade.Comment: IUPAP Centennial Lecture, Neutrino 2000; related information:
http://www.sns.ias.edu/~jn
Solar neutrino interactions: Using charged currents at SNO to tell neutral currents at Super-Kamiokande
In the presence of flavor oscillations, muon and tau neutrinos can contribute
to the Super-Kamiokande (SK) solar neutrino signal through the neutral current
process \nu_{\mu,\tau} e^{-}\to \nu_{\mu,\tau} e^{-}. We show how to separate
the \nu_e and \nu_{\mu,\tau} event rates in SK in a model independent way, by
using the rate of the charged current process \nu_e d \to p p e^{-} from the
Sudbury Neutrino Observatory (SNO) experiment, with an appropriate choice of
the SK and SNO energy thresholds. Under the additional hypothesis of no
oscillations into sterile states, we also show how to determine the absolute
^{8}B neutrino flux from the same data set, independently of the \nu_e survival
probability.Comment: 14 pages (RevTeX), incl. 3 figures (epsf), submitted to Phys. ReV.
Effect of Coulomb collisions on time variations of the solar neutrino flux
We consider the possibility of time variations of the solar neutrino flux due
to the radial motion of the Earth and neutrino interference effects. We
calculate the time variations of the detected neutrino flux and the extent to
which they are suppressed by Coulomb collisions of the neutrino emitting
nuclei. To properly treat the collisions, it is necessary to simultaneously
include in our analysis all other significant physical decoherence effects: the
energy averaging and the averaging over the position of neutrino emission.
A simple and clear physical picture of the time dependent solar neutrino
problem is presented and qualitative coherence criteria are discussed. Exact
results for the detected neutrino flux and its time variations are obtained for
both the case of a solar neutrino line, and the case of the continuous neutrino
spectrum with a Gaussian shape of the energy response function of the neutrino
detector. We give accurate constraints on the vacuum mixing angle and the
neutrino masses required for flux time variations to not be suppressed.
Pac(s): 26.65.+t, 14.60.Pq, 96.60.JwComment: 43 pages, 8 figures, 4 appendices; changed title, MSW jump
probability formula and figure
Bounds on neutrino magnetic moment tensor from solar neutrinos
Solar neutrinos with non-zero magnetic moments will contribute to the
electron scattering rates in the Super-Kamiokande experiment. The magnetic
moment scattering events in Super-K can be accommodated in the standard VO or
MSW solutions by a change of the parameter space of mass square difference and
mixing angle-but the shifted neutrino parameters obtained from Super-K will
(for some values of neutrino magnetic moments) become incompatible with the
fits from SNO, Gallium and Chlorine experiments. We compute the upper bounds on
the Dirac and Majorana magnetic moments of solar neutrinos by simultaneously
fitting all the observed solar neutrino rates. The bounds the magnetic moment
matrix elements are of the order of 10^{-10} Bohr magnetron.Comment: 9 pages latex file with 6 figures; References added, typos corrected,
matches version to appear in Phys Rev
The luminosity constraint on solar neutrino fluxes
A specific linear combination of the total solar neutrino fluxes must equal
the measured solar photon luminosity if nuclear fusion reactions among light
elements are responsible for solar energy generation. This luminosity
constraint, previously used in a limited form in testing the no neutrino
oscillation hypothesis, is derived in a generality that includes all of the
relevant solar neutrino fluxes and which is suitable for analyzing the results
of many different solar neutrino experiments. With or without allowing for
neutrino oscillations, the generalized luminosity constraint can be used in
future analyses of solar neutrino data. Accurate numerical values for the
linear coefficients are provided.Comment: related material at http://www.sns.ias.edu/~jn
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