1,187 research outputs found
Solar neutrino physics with low-threshold dark matter detectors
Dark matter detectors will soon be sensitive to Solar neutrinos via two
distinct channels: coherent neutrino-nucleus scattering and neutrino electron
elastic scattering. We establish an analysis method for extracting Solar model
properties and neutrino properties from these measurements, including the
possible effects of sterile neutrinos which have been hinted at by some reactor
experiments and cosmological measurements. Even including sterile neutrinos,
through the coherent scattering channel a 1 ton-year exposure with a
low-threshold Germanium detector could improve on the current measurement of
the normalization of the B Solar neutrino flux down to 3% or less.
Combining with the elastic scattering data will provide constraints on both the
high and low energy survival probability, and will improve on the uncertainty
on the active-to-sterile mixing angle by a factor of two. This sensitivity to
active-to-sterile transitions is competitive and complementary to forthcoming
dedicated short baseline sterile neutrino searches with nuclear decays.Comment: 12 pages, 4 figures, 3 table
Implication of neutrino backgrounds on the reach of next generation dark matter direct detection experiments
As direct dark matter experiments continue to increase in size, they will
become sensitive to neutrinos from astrophysical sources. For experiments that
do not have directional sensitivity, coherent neutrino scattering (CNS) from
several sources represents an important background to understand, as it can
almost perfectly mimic an authentic WIMP signal. Here we explore in detail the
effect of neutrino backgrounds on the discovery potential of WIMPs over the
entire mass range of 500 MeV to 10 TeV. We show that, given the theoretical and
measured uncertainties on the neutrino backgrounds, direct detection
experiments lose sensitivity to light (~10 GeV) and heavy (~100 GeV) WIMPs with
a spin-independent cross section below 10^{-45} cm^2 and 10^{-49} cm^2,
respectively.Comment: 15 pages, 12 figures, 7Be fluxes revised, conclusions unchange
Complementarity of dark matter detectors in light of the neutrino background
Direct detection dark matter experiments looking for WIMP-nucleus elastic
scattering will soon be sensitive to an irreducible background from neutrinos
which will drastically affect their discovery potential. Here we explore how
the neutrino background will affect future ton-scale experiments considering
both spin-dependent and spin-independent interactions. We show that combining
data from experiments using different targets can improve the dark matter
discovery potential due to target complementarity. We find that in the context
of spin-dependent interactions, combining results from several targets can
greatly enhance the subtraction of the neutrino background for WIMP masses
below 10 GeV/c and therefore probe dark matter models to lower
cross-sections. In the context of target complementarity, we also explore how
one can tune the relative exposures of different target materials to optimize
the WIMP discovery potential.Comment: 13 pages, 12 figures, 3 table
Vibrations on pulse tube based Dry Dilution Refrigerators for low noise measurements
Dry Dilution Refrigerators (DDR) based on pulse tube cryo-coolers have
started to replace Wet Dilution Refrigerators (WDR) due to the ease and low
cost of operation. However these advantages come at the cost of increased
vibrations, induced by the pulse tube. In this work, we present the vibration
measurements performed on three different commercial DDRs. We describe in
detail the vibration measurement system we assembled, based on commercial
accelerometers, conditioner and DAQ, and examined the effects of the various
damping solutions utilized on three different DDRs, both in the low and high
frequency regions. Finally, we ran low temperature, pseudo-massive (30 and 250
g) germanium bolometers in the best vibration-performing system under study and
report on the results
Orientation and Alignment Echoes
We present what is probably the simplest classical system featuring the echo
phenomenon - a collection of randomly oriented free rotors with dispersed
rotational velocities. Following excitation by a pair of time-delayed impulsive
kicks, the mean orientation/alignment of the ensemble exhibits multiple echoes
and fractional echoes. We elucidate the mechanism of the echo formation by
kick-induced filamentation of phase space, and provide the first experimental
demonstration of classical alignment echoes in a thermal gas of CO_2 molecules
excited by a pair of femtosecond laser pulses
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