213 research outputs found
Solar Neutrinos as Background in Direct Dark Matter Searches
The coherent contribution of all neutrons in neutrino nucleus scattering due
to the neutral current is examined considering the boron solar neutrinos. These
neutrinos could potentially become a source of background in the future dark
matter searches aiming at nucleon cross sections in the region well below the
few events per ton per year.Comment: 6 pages, 5 figures, Submitted for the DSU proceedings to be published
by the American institute of Physics (AIP). References adde
Coherent Neutral Current Neutrino-Nucleus Scattering at a Spallation Source; a Valuable Experimental Probe
The coherent contribution of all neutrons in neutrino nucleus scattering due
to the neutral current is examined considering the Spallation Neutron Source
(SNS) as a source of neutrinos. SNS is a prolific pulsed source of electron and
muon neutrinos as well as muon antineutrinos.Comment: 15 LaTex pages, 14 figures, 3 Table
Cold Dark Matter detection in SUSY models at large tan(beta)
We study the direct detection rate for SUSY cold dark matter (CDM) predicted
by the minimal supersymmetric standard model with universal boundary conditions
and large values for tan(beta). The relic abundance of the lightest
supersymmetric particle (LSP), assumed to be approximately a bino, is obtained
by including its coannihilations with the next-to-lightest supersymmetric
particle (NLSP), which is the lightest s-tau. The cosmological constraint on
this quantity severely limits the allowed SUSY parameter space, especially in
the case the CP-even Higgs has mass of around 114 GeV. We find that for large
tan(beta) it is possible to find a subsection of the allowed parameter space,
which yields detectable rates in the currently planned experiments.Comment: Changes in text and figure
On the keV sterile neutrino search in electron capture
A joint effort of cryogenic microcalorimetry (CM) and high-precision
Penning-trap mass spectrometry (PT-MS) in investigating atomic orbital electron
capture (EC) can shed light on the possible existence of heavy sterile
neutrinos with masses from 0.5 to 100 keV. Sterile neutrinos are expected to
perturb the shape of the atomic de-excitation spectrum measured by CM after a
capture of the atomic orbital electrons by a nucleus. This effect should be
observable in the ratios of the capture probabilities from different orbits.
The sensitivity of the ratio values to the contribution of sterile neutrinos
strongly depends on how accurately the mass difference between the parent and
the daughter nuclides of EC-transitions can be measured by, e.g., PT-MS. A
comparison of such probability ratios in different isotopes of a certain
chemical element allows one to exclude many systematic uncertainties and thus
could make feasible a determination of the contribution of sterile neutrinos on
a level below 1%. Several electron capture transitions suitable for such
measurements are discussed.Comment: 16 pages, 9 figures, 2 table
Ultra low energy results and their impact to dark matter and low energy neutrino physics
We present ultra low energy results taken with the novel Spherical
Proportional Counter. The energy threshold has been pushed down to about 25 eV
and single electrons are clearly collected and detected. To reach such
performance low energy calibration systems have been successfully developed: -
A pulsed UV lamp extracting photoelectrons from the inner surface of the
detector - Various radioactive sources allowing low energy peaks through
fluorescence processes. The bench mark result is the observation of a well
resolved peak at 270 eV due to carbon fluorescence which is unique performance
for such large-massive detector. It opens a new window in dark matter and low
energy neutrino search and may allow detection of neutrinos from a nuclear
reactor or from supernova via neutrino-nucleus elastic scatteringComment: 14 pages,16 figure
Neutrinoless Double Beta Decay in Gauge Theories
Neutrinoless double beta decay is a very important process both from the
particle and nuclear physics point of view. Its observation will severely
constrain the existing models and signal that the neutrinos are massive
Majorana particles. From the elementary particle point of view it pops up in
almost every model. In addition to the traditional mechanisms, like the
neutrino mass, the admixture of right handed currents etc, it may occur due to
the R-parity violating supersymmetric (SUSY) interactions. From the nuclear
physics point of view it is challenging, because: 1) The relevant nuclei have
complicated nuclear structure. 2) The energetically allowed transitions are
exhaust a small part of all the strength. 3) One must cope with the short
distance behavior of the transition operators, especially when the intermediate
particles are heavy (eg in SUSY models). Thus novel effects, like the double
beta decay of pions in flight between nucleons, have to be considered. 4) The
intermediate momenta involved are about 100 MeV. Thus one has to take into
account possible momentum dependent terms in the nucleon current. We find that,
for the mass mechanism, such modifications of the nucleon current for light
neutrinos reduce the nuclear matrix elements by about 25 per cent, almost
regardless of the nuclear model. In the case of heavy neutrinos the effect is
much larger and model dependent.
Taking the above effects into account, the available nuclear matrix elements
for the experimentally interesting nuclei A = 76, 82, 96, 100, 116, 128, 130,
136 and 150 and the experimental limits on the life times we have extracted new
stringent limits on the average neutrino mass and on the R-parity violating
coupling for various SUSY models.Comment: Latex, 24 pages, 1 postscript figure, uses iopconf.st
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