584 research outputs found
The solar neutrino problem after three hundred days of data at SuperKamiokande
We present an updated analysis of the solar neutrino problem in terms of both
Mikheyev-Smirnov-Wolfenstein (MSW) and vacuum neutrino oscillations, with the
inclusion of the preliminary data collected by the SuperKamiokande experiment
during 306.3 days of operation. In particular, the observed energy spectrum of
the recoil electrons from 8B neutrino scattering is discussed in detail and is
used to constrain the mass-mixing parameter space. It is shown that: 1) the
small mixing MSW solution is preferred over the large mixing one; 2) the vacuum
oscillation solutions are strongly constrained by the energy spectrum
measurement; and 3) the detection of a possible semiannual modulation of the 8B
\nu flux due to vacuum oscillations should require at least one more year of
operation of SuperKamiokande.Comment: 15 pages (RevTeX) + 8 figures (postscript). Requires epsfig.st
The Reactor Antineutrino Anomaly
Recently new reactor antineutrino spectra have been provided for 235U, 239Pu,
241Pu and 238U, increasing the mean flux by about 3 percent. To good
approximation, this reevaluation applies to all reactor neutrino experiments.
The synthesis of published experiments at reactor-detector distances <100 m
leads to a ratio of observed event rate to predicted rate of 0.976(0.024). With
our new flux evaluation, this ratio shifts to 0.943(0.023), leading to a
deviation from unity at 98.6% C.L. which we call the reactor antineutrino
anomaly. The compatibility of our results with the existence of a fourth
non-standard neutrino state driving neutrino oscillations at short distances is
discussed. The combined analysis of reactor data, gallium solar neutrino
calibration experiments, and MiniBooNE-neutrino data disfavors the
no-oscillation hypothesis at 99.8% C.L. The oscillation parameters are such
that |Delta m_{new}^2|>1.5 eV^2 (95%) and sin^2(2\theta_{new})=0.14(0.08)
(95%). Constraints on the theta13 neutrino mixing angle are revised.Comment: 19 pages, 15 figures ; v2/3 include typos corrected ; v4 final
version: add 5 Rovno & 2 Savannah River results + add additional constistency
checks + add a discussion on the inverse beta decay cross section
normlizatio
Generic First Order Orientation Transition of Vortex Lattices in Type II Superconductors
First order transition of vortex lattices (VL) observed in various
superconductors with four-fold symmetry is explained microscopically by
quasi-classical Eilenberger theory combined with nonlocal London theory. This
transition is intrinsic in the generic successive VL phase transition due to
either gap or Fermi velocity anisotropies. This is also suggested by the
electronic states around vortices. Ultimate origin of this phenomenon is
attributed to some what hidden frustrations of a spontaneous symmetry broken
hexagonal VL on the underlying four-fold crystalline symmetry.Comment: 4 pages, 5 figures, some typos are correcte
Gamow-Teller Strengths of the Inverse-Beta Transition 176Yb --> 176Lu for Spectroscopy of Proton-Proton and other sub-MeV Solar Neutrinos
Discrete Gamow-Teller (GT) transitions, 176Yb-->176Lu at low excitation
energies have been measured via the (3He,t) reaction at 450 MeV and at 0
degrees. For 176Yb, two low-lying states are observed, setting low thresholds
Q(neutrino)=301 and 445 keV for neutrino capture. Capture rates estimated from
the measured GT strengths, the simple two-state excitation structure, and the
low Q(neutrino) in Yb--Lu indicate that Yb-based neutrino-detectors are well
suited for a direct measurement of the complete sub-MeV solar electron-neutrino
spectrum (including pp neutrinos) where definitive effects of flavor conversion
are expected
Beta decay of 115-In to the first excited level of 115-Sn: Potential outcome for neutrino mass
Recent observation of beta decay of 115-In to the first excited level of
115-Sn with an extremely low Q_beta value (Q_beta ~ 1 keV) could be used to set
a limit on neutrino mass. To give restriction potentially competitive with
those extracted from experiments with 3-H (~2 eV) and 187-Re (~15 eV), atomic
mass difference between 115-In and 115-Sn and energy of the first 115-Sn level
should be remeasured with higher accuracy (possibly of the order of ~1 eV).Comment: 9 pages, 3 figures; talk at the NANP'05 Conferenc
The NuMI Neutrino Beam and Potential for an Off-Axis Experiment
The Neutrinos at the Main Injector (NuMI) facility at Fermilab is under
construction and due to begin operations in late 2004. NuMI will deliver an
intense beam of variable energy 2-20 GeV directed into the Earth at
58 mrad. Several aspects of the design are reviewed, and potential limitations
to the ultimate neutrino flux are described. In addition, potential
measurements of neutrino mixing properties are described.Comment: talk given at NuFact '02, Imperial College London, proceedings to
appear in J. Phys. G, revised to add a referenc
Kinetic Theory of Flux Line Hydrodynamics:LIQUID Phase with Disorder
We study the Langevin dynamics of flux lines of high--T superconductors
in the presence of random quenched pinning. The hydrodynamic theory for the
densities is derived by starting with the microscopic model for the flux-line
liquid. The dynamic functional is expressed as an expansion in the dynamic
order parameter and the corresponding response field. We treat the model within
the Gaussian approximation and calculate the dynamic structure function in the
presence of pinning disorder. The disorder leads to an additive static peak
proportional to the disorder strength. On length scales larger than the line
static transverse wandering length and at long times, we recover the
hydrodynamic results of simple frictional diffusion, with interactions
additively renormalizing the relaxational rate. On shorter length and time
scales line internal degrees of freedom significantly modify the dynamics by
generating wavevector-dependent corrections to the density relaxation rate.Comment: 61 pages and 6 figures available upon request, plain TEX using
Harvard macro
GNO Solar Neutrino Observations: Results for GNOI
We report the first GNO solar neutrino results for the measuring period GNOI,
solar exposure time May 20, 1998 till January 12, 2000. In the present
analysis, counting results for solar runs SR1 - SR19 were used till April 4,
2000. With counting completed for all but the last 3 runs (SR17 - SR19), the
GNO I result is [65.8 +10.2 -9.6 (stat.) +3.4 -3.6 (syst.)]SNU (1sigma) or
[65.8 + 10.7 -10.2 (incl. syst.)]SNU (1sigma) with errors combined. This may be
compared to the result for Gallex(I-IV), which is [77.5 +7.6 -7.8 (incl.
syst.)] SNU (1sigma). A combined result from both GNOI and Gallex(I-IV)
together is [74.1 + 6.7 -6.8 (incl. syst.)] SNU (1sigma).Comment: submitted to Physics Letters B, June 2000. PACS: 26.65. +t ; 14.60
Pq. Corresponding author: [email protected] ; [email protected]
A Study of the Day - Night Effect for the Super - Kamiokande Detector: I. Time Averaged Solar Neutrino Survival Probability
This is the first of two articles aimed at providing comprehensive
predictions for the day-night (D-N) effect for the Super-Kamiokande detector in
the case of the MSW \nu_e \to \numt transition solution of the solar neutrino
problem. The one-year averaged probability of survival of the solar \nue
crossing the Earth mantle, the core, the inner 2/3 of the core, and the (core +
mantle) is calculated with high precision (better than 1%) using the elliptical
orbit approximation (EOA) to describe the Earth motion around the Sun. Results
for the survival probability in the indicated cases are obtained for a large
set of values of the MSW transition parameters and
from the ``conservative'' regions of the MSW solution,
derived by taking into account possible relatively large uncertainties in the
values of the B and Be neutrino fluxes. Our results show that the
one-year averaged D-N asymmetry in the survival probability for
neutrinos crossing the Earth core can be, in the case of , larger than the asymmetry in the probability for (only mantle
crossing + core crossing) neutrinos by a factor of up to six. The enhancement
is larger in the case of neutrinos crossing the inner 2/3 of the core. This
indicates that the Super-Kamiokande experiment might be able to test the
region of the MSW solution of the solar neutrino
problem by performing selective D-N asymmetry measurements.Comment: LaTeX2e - 18 Text Pages + 21 figures = 39 Pages. - Figures in PS +
text file sk1b14.tex requires two auxiliary files (included
White paper: CeLAND - Investigation of the reactor antineutrino anomaly with an intense 144Ce-144Pr antineutrino source in KamLAND
We propose to test for short baseline neutrino oscillations, implied by the
recent reevaluation of the reactor antineutrino flux and by anomalous results
from the gallium solar neutrino detectors. The test will consist of producing a
75 kCi 144Ce - 144Pr antineutrino source to be deployed in the Kamioka Liquid
Scintillator Anti-Neutrino Detector (KamLAND). KamLAND's 13m diameter target
volume provides a suitable environment to measure energy and position
dependence of the detected neutrino flux. A characteristic oscillation pattern
would be visible for a baseline of about 10 m or less, providing a very clean
signal of neutrino disappearance into a yet-unknown, "sterile" state. Such a
measurement will be free of any reactor-related uncertainties. After 1.5 years
of data taking the Reactor Antineutrino Anomaly parameter space will be tested
at > 95% C.L.Comment: White paper prepared for Snowmass-2013; slightly different author
lis
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