2,609 research outputs found
Simulation of the Directional Dark Matter Detector (D3) and Directional Neutron Observer (DiNO)
Preliminary simulation and optimization studies of the Directional Dark
Matter Detector and the Directional Neutron Observer are presented. These
studies show that the neutron interaction with the gas-target in these
detectors is treated correctly by GEANT4 and that by lowering the pressure, the
sensitivity to low-mass WIMP candidates is increased. The use of negative ion
drift might allow us to search the WIMP mass region suggested by the results of
the non-directional experiments DAMA/LIBRA, CoGeNT and CRESST-II.Comment: Proceedings of the 3rd International conference on Directional
Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10 June 201
Cerenkov angle and charge reconstruction with the RICH detector of the AMS experiment
The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the
International Space Station (ISS) will be equipped with a proximity focusing
Ring Imaging Cerenkov (RICH) detector, for measurements of particle electric
charge and velocity. In this note, two possible methods for reconstructing the
Cerenkov angle and the electric charge with the RICH, are discussed. A
Likelihood method for the Cerenkov angle reconstruction was applied leading to
a velocity determination for protons with a resolution of around 0.1%. The
existence of a large fraction of background photons which can vary from event
to event, implied a charge reconstruction method based on an overall efficiency
estimation on an event-by-event basis.Comment: Proceedings submitted to RICH 2002 (Pylos-Greece
Quantum-Gravitational Diffusion and Stochastic Fluctuations in the Velocity of Light
We argue that quantum-gravitational fluctuations in the space-time background
give the vacuum non-trivial optical properties that include diffusion and
consequent uncertainties in the arrival times of photons, causing stochastic
fluctuations in the velocity of light ``in vacuo''. Our proposal is motivated
within a Liouville string formulation of quantum gravity that also suggests a
frequency-dependent refractive index of the particle vacuum. We construct an
explicit realization by treating photon propagation through quantum excitations
of -brane fluctuations in the space-time foam. These are described by
higher-genus string effects, that lead to stochastic fluctuations in couplings,
and hence in the velocity of light. We discuss the possibilities of
constraining or measuring photon diffusion ``in vacuo'' via -ray
observations of distant astrophysical sources.Comment: 17 pages LATEX, uses axodraw style fil
First Dark Matter Search Results from a Surface Run of the 10-L DMTPC Directional Dark Matter Detector
The Dark Matter Time Projection Chamber (DMTPC) is a low pressure (75 Torr
CF4) 10 liter detector capable of measuring the vector direction of nuclear
recoils with the goal of directional dark matter detection. In this paper we
present the first dark matter limit from DMTPC. In an analysis window of 80-200
keV recoil energy, based on a 35.7 g-day exposure, we set a 90% C.L. upper
limit on the spin-dependent WIMP-proton cross section of 2.0 x 10^{-33} cm^{2}
for 115 GeV/c^2 dark matter particle mass.Comment: accepted for publication in Physics Letters
Scintillators and Cherenkov detectors for the registration of 10.8 MeV gamma rays
© Published under licence by IOP Publishing Ltd. The identification of nitrogen by neutron activation has been utilized in both explosive detection and in-vivo metabolic analysis. The 10.8 MeV gamma ray line emitted by thermal neutron capture provides a unique signature, however, due to its high energy its registration is non-trivial. Conventional approaches have used large dense inorganic scintillators which inevitably entail considerable expense. We examine the capabilities of arrays of smaller scintillation detectors and the use of glass Cherenkov detectors as an alternative
Antimatter in the Universe
Cosmological models which predict a large amount of antimatter in the
Universe are reviewed. Observational signatures and searches for cosmic
antimatter are briefly considered. A short discussion of new long range forces
which might be associated with matter and antimatter is presented.Comment: 17 pages + 2 figure
MIMAC : A micro-tpc matrix for directional detection of dark matter
Directional detection of non-baryonic Dark Matter is a promising search
strategy for discriminating WIMP events from background. However, this strategy
requires both a precise measurement of the energy down to a few keV and 3D
reconstruction of tracks down to a few mm. To achieve this goal, the MIMAC
project has been developed. It is based on a gaseous micro-TPC matrix, filled
with CF4 and CHF3. The first results on low energy nuclear recoils (H, F)
obtained with a low mono-energetic neutron field are presented. The discovery
potential of this search strategy is discussed and illustrated by a realistic
case accessible to MIMAC.Comment: 6 pages, Proc. of the fifth international symposium on large TPCs for
low energy rare event detection, Paris, France, Dec. 2010. To appear in
Journal of Physic
Search for Magnetic Monopoles Trapped in Matter
There have been many searches for magnetic monopoles in flight, but few for
monopoles in matter. We have searched for magnetic monopoles in meteorites,
schists, ferromanganese nodules, iron ores and other materials. The detector
was a superconducting induction coil connected to a SQUID (Superconducting
Quantum Interference Device) with a room temperature bore 15 cm in diameter. We
tested a total of more than 331 kg of material including 112 kg of meteorites.
We found no monopole and conclude the overall monopole/nucleon ratio in the
samples is with a 90\% confidence level.Comment: 6 pages, rev tex, no figure
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