1,308 research outputs found
Low-energy electronic recoil in xenon detectors by solar neutrinos
Low-energy electronic recoil caused by solar neutrinos in multi-ton xenon
detectors is an important subject not only because it is a source of the
irreducible background for direct searches of weakly-interacting massive
particles (WIMPs), but also because it provides a viable way to measure the
solar and neutrinos at the precision level of current
standard solar model predictions. In this work we perform
many-body calculations for the structure, photoionization, and
neutrino-ionization of xenon. It is found that the atomic binding effect yields
a sizable suppression to the neutrino-electron scattering cross section at low
recoil energies. Compared with the previous calculation based on the free
electron picture, our calculated event rate of electronic recoil in the same
detector configuration is reduced by about . We present in this paper the
electronic recoil rate spectrum in the energy window of 100 eV - 30 keV with
the standard per ton per year normalization for xenon detectors, and discuss
its implication for low energy solar neutrino detection (as the signal) and
WIMP search (as a source of background).Comment: 12 pages, 3 figure
Atomic ionization by sterile-to-active neutrino conversion and constraints on dark matter sterile neutrinos with germanium detectors
The transition magnetic moment of a sterile-to-active neutrino conversion
gives rise to not only radiative decay of a sterile neutrino, but also its
non-standard interaction (NSI) with matter. For sterile neutrinos of keV-mass
as dark matter candidates, their decay signals are actively searched for in
cosmic X-ray spectra. In this work, we consider the NSI that leads to atomic
ionization, which can be detected by direct dark matter experiments. It is
found that this inelastic scattering process for a nonrelativistic sterile
neutrino has a pronounced enhancement in the differential cross section at
energy transfer about half of its mass, manifesting experimentally as peaks in
the measurable energy spectra. The enhancement effects gradually smear out as
the sterile neutrino becomes relativistic. Using data taken with germanium
detectors that have fine energy resolution in keV and sub-keV regimes,
constraints on sterile neutrino mass and its transition magnetic moment are
derived and compared with those from astrophysical observations
Overview in Big Data Analysis of the Japanese Defense System: Ambiguous Adjustment to a Strategic Environment Change
Taiwan and Japan are both maritime countries. The natural resources in the territory are quite limited. Due to this inherent limitation, both Taiwan and Japan rely on trade to safeguard their own economic interests. Therefore, defending the maritime traffic lines and ensuring maritime interests are important missions of the Taiwan and Japan defense systems. The recent increasingly harsh international situation in the Asia-Pacific region has seriously affected the security and stability of the surrounding areas. Invisible also poses many challenges to Taiwan’s maritime rights and interests, so it is a reflection on Taiwan’s future development by understanding the Japanese defense system
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