1,701 research outputs found
Comparing readout strategies to directly detect dark matter
Over the past decades, several ideas and technologies have been developed to
directly detect WIMP from the galactic halo. All these detection strategies
share the common goal of discriminating a WIMP signal from the residual
backgrounds. By directly detecting WIMPs, one can measure some or all of the
observables associated to each nuclear recoil candidates, such as their energy
and direction. In this study, we compare and examine the discovery potentials
of each readout strategies from counting only (bubble chambers) to directional
detectors (Time Projection Chambers) with 1d-, 2d-, and 3d-sensitivity. Using a
profile likelihood analysis, we show that, in the case of a large and
irreducible background contamination characterized by an energy distribution
similar to the expected WIMP signal, directional information can improve the
sensitivity of the experiment by several orders of magnitude. We also found
that 1d directional detection is only less effective than a full 3d directional
sensitivity by about a factor of 3, or 10 if we assume no sense recognition,
still improving by a factor of 2 or more if only the energy of the events is
being measured.Comment: 9 pages, 5 figures, discussion about annual modulation added, matches
version published in PR
Track reconstruction with MIMAC
Directional detection of Dark Matter is a promising search strategy. However,
to perform such kind of detection, the recoiling tracks have to be accurately
reconstructed: direction, sense and position in the detector volume. In order
to optimize the track reconstruction and to fully exploit the data from the
MIMAC detector, we developed a likelihood method dedicated to the track
reconstruction. This likelihood approach requires a full simulation of track
measurements with MIMAC in order to compare real tracks to simulated ones.
Finally, we found that the MIMAC detector should have the required performance
to perform a competitive directional detection of Dark Matter.Comment: 9 pages, 6 figures; Proceedings of the 3rd International conference
on Directional Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10
June 201
A review on the discovery reach of Dark Matter directional detection
Directional detection of galactic Dark Matter offers a unique opportunity to
identify Weakly Interacting Massive Particle (WIMP) events as such. Depending
on the unknown WIMP-nucleon cross section, directional detection may be used to
: exclude Dark Matter, discover galactic Dark Matter with a high significance
or constrain WIMP and halo properties. We review the discovery reach of Dark
Matter directional detection.Comment: Proceedings of the 4th international conference on Directional
Detection of Dark Matter (CYGNUS 2013), 10-12 June 2013, Toyama, Japa
Identification of Dark Matter with directional detection
Directional detection is a promising search strategy to discover galactic
Dark Matter. Taking advantage on the rotation of the Solar system around the
Galactic center through the Dark Matter halo, it allows to show a direction
dependence of WIMP events. Data of directional detectors are composed of energy
and a 3D track for each recoiling nuclei. Here, we present a Bayesian analysis
method dedicated to data from upcoming directional detectors. However, we focus
only on the angular part of the event distribution, arguing that the energy
part of the background distribution is unknown. Two different cases are
considered: a positive or a null detection of Dark Matter. In the first
scenario, we will present a map-based likelihood method allowing to recover the
main incoming direction of the signal and its significance, thus proving its
Galactic origin. In the second scenario, a new statistical method is proposed.
It is based on an extended likelihood in order to set robust and competitive
exclusion limits. This method has been compared to two other methods and has
been shown to be optimal in any detector configurations. Eventually, prospects
for the MIMAC project are presented in the case of a 10 kg CF4 detector with an
exposition time of 3 years.Comment: Proceeding of the 8th International Workshop on the Identification of
Dark Matter (IDM 2010), July 2010, Montpellier, France. To appear in
Proceedings of Science (PoS
What do we really know about Dark Energy?
In this paper I discuss what we truly know about dark energy. I shall argue
that up to date our single indication for the existence of dark energy comes
from distance measurements and their relation to redshift. Supernovae, CMB
anisotropies and observations of baryon acoustic oscillations, they all simply
tell us that the observed distance to a given redshift is larger than the one
expected from a Friedmann Lemaitre universe with matter only and the locally
measured Hubble parameter.Comment: invited talk at the meeting "Cosmological Tests of General
Relativity" at the Kavli Royal Society Center for the Advancement of Science
organized by Rachel Bean, Pedro Ferreira and Andy Taylor. 14p 2 figs. revised
version: updated to match version in print in Phil. Trans. R. Soc.
Directional detection of galactic dark matter
Directional detection is a promising Dark Matter search strategy. Taking
advantage on the rotation of the Solar system around the galactic center
through the Dark Matter halo, it allows to show a direction dependence of WIMP
events that may be a powerful tool to identify genuine WIMP events as such.
Directional detection strategy requires the simultaneous measurement of the
energy and the 3D track of low energy recoils, which is a common challenge for
all current projects of directional detectors.Comment: Proceedings of UCLA Dark Matter 2012, 10th Symposium on Sources and
Detection of Dark Matter and Dark Energy in the Universe, Marina del Rey
Marriott, CA, USA, February 22-24, 201
Evaluation of nickel-hydrogen battery for space application
Results of electrical space qualification tests of nickel-hydrogen battery type HR 23S are presented. The results obtained for the nickel-cadmium battery type VO 23S are similar except that the voltage level and the charge conservation characteristics vary significantly. The electrical and thermal characteristics permit predictions of the following optimal applications: charge coefficient in the order of 1.3 to 1.4 at 20C; charge current density higher than C/10 at 20C; discharge current density from C/10 to C/3 at 20C; maximum discharge temperature: OC; storage temperature: -20C
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
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