157 research outputs found
Inverse beta decay reaction in Th and U fission antineutrino flux
Energy spectra of antineutrinos coming from Th and U
neutron-induced fission are calculated, relevant inverse beta decay
positron spectra and total cross sections are
found. This study is stimulated by a hypothesis that a self-sustained nuclear
chain reaction is burning at the center of the Earth ("Georeactor"). The
Georeactor, according to the author of this idea, provides energy necessary to
sustain the Earth's magnetic field. The Georeactor's nuclear fuel is U
and, probably, Th and U. Results of present study may appear to
be useful in future experiments aimed to test the Georector hypothesis and to
estimate its fuel components as a part of developments in geophysics and
astrophysics based on observations of low energy antineutrinos in Nature.Comment: 6 pages in LaTeX and 2 ps figures. Submitted to Physics of Atomic
Nucle
On Possibilities of Studying of Supernova Neutrinos at BAKSAN
We consider the possibilities of studying a supernova collapse neutrino burst
at Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy
of Sciences) using the prposed 5-kt target-mass liquid scintillation
spectrometer. Attention is given to the influence of mixing angle
on the expected rates and spectra of neutrino events
Neutrino Geophysics at Baksan I: Possible Detection of Georeactor Antineutrinos
J.M. Herndon in 90-s proposed a natural nuclear fission georeactor at the
center of the Earth with a power output of 3-10 TW as an energy source to
sustain the Earth magnetic field. R.S. Raghavan in 2002 y. pointed out that
under certain condition antineutrinos generated in georeactor can be detected
using massive scintillation detectors. We consider the underground Baksan
Neutrino Observatory (4800 m.w.e.) as a possible site for developments in
Geoneutrino physics. Here the intrinsic background level of less than one
event/year in a liquid scintillation ~1000 target ton detector can be achieved
and the main source of background is the antineutrino flux from power reactors.
We find that this flux is ~10 times lower than at KamLAND detector site and two
times lower than at Gran Sasso laboratory and thus at Baksan the georeactor
hypothesis can be conclusively tested. We also discuss possible search for
composition of georector burning nuclear fuel by analysis of the antineutrino
energy spectrum.Comment: 7 pages in LaTeX, 3 PS figures, Submitted to Physics of Atomic Nucle
Present and Future Experiments in Non-equilibrium Reactor Antineutrino Energy Spectrum
Considerable efforts that have been undertaken in the recent years in low
energy antineutrino experiments require further systematic investigations in
line of reactor antineutrino spectroscopy as a metrological basis of these
experiments. We consider some effects associated with the non-equilibrium of
reactor antineutrino radiation and residual antineutrino emission from spent
reactor fuel in contemporary antineutrino experiments.Comment: 7 pages, 5 figures; Talk presented at International Conference
NANP-2005, Dubna, Russia, Jun.-2005; Submitted to Phys. Atom. Nuc
RICE Limits on the Diffuse Ultra-High Energy Neutrino Flux
We present new limits on ultra-high energy neutrino fluxes above 100 PeV
based on data collected by the Radio Ice Cherenkov Experiment (RICE) at the
South Pole from 1999-2005. We discuss estimation of backgrounds, calibration
and data analysis algorithms (both on-line and off-line), procedures used for
the dedicated neutrino search, and refinements in our Monte Carlo (MC)
simulation, including recent in situ measurements of the complex ice dielectric
constant. An enlarged data set and a more detailed study of hadronic showers
results in a sensitivity improvement of more than one order of magnitude
compared to our previously published results. Examination of the full RICE data
set yields zero acceptable neutrino candidates, resulting in 95%
confidence-level model dependent limits on the flux
(E_\nu)^2(d\phi/dE_\nu)<10^{-6} GeV/(cm^2s~sr}) in the energy range 10^{17}<
E_\nu< 10^{20} eV. The new RICE results rule out the most intense flux model
projections at 95% confidence level.Comment: Submitted to Astropart. Phy
The Case for a Low Extragalactic Gamma-ray Background
Measurements of the diffuse extragalactic gamma-ray background (EGRB) are
complicated by a strong Galactic foreground. Estimates of the EGRB flux and
spectrum, obtained by modeling the Galactic emission, have produced a variety
of (sometimes conflicting) results. The latest analysis of the EGRET data found
an isotropic flux I_x=1.45+-0.05 above 100 MeV, in units of 10^-5 s^-1 cm^-2
sr^-1. We analyze the EGRET data in search for robust constraints on the EGRB
flux, finding the gamma-ray sky strongly dominated by Galactic foreground even
at high latitudes, with no conclusive evidence for an additional isotropic
component. The gamma-ray intensity measured towards the Galactic poles is
similar to or lower than previous estimates of I_x. The high latitude profile
of the gamma-ray data is disk-like for 40<|b[deg]|<70, and even steeper for
|b|>70; overall it exhibits strong Galactic features and is well fit by a
simple Galactic model. Based on the |b|>40 data we find that I_x<0.5 at a 99%
confidence level, with evidence for a much lower flux. We show that
correlations with Galactic tracers, previously used to identify the Galactic
foreground and estimate I_x, are not satisfactory; the results depend on the
tracers used and on the part of the sky examined, because the Galactic emission
is not linear in the Galactic tracers and exhibits spectral variations across
the sky. The low EGRB flux favored by our analysis places stringent limits on
extragalactic scenarios involving gamma-ray emission, such as radiation from
blazars, intergalactic shocks and production of ultra-high energy cosmic rays
and neutrinos. We suggest methods by which future gamma-ray missions such as
GLAST and AGILE could indirectly identify the EGRB.Comment: Accepted for publication in JCAP. Increased sizes of polar regions
examined, and added discussion of spectral data. Results unchange
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