1,728 research outputs found
New results from DAMA/LIBRA
DAMA/LIBRA is running at the Gran Sasso National Laboratory of the I.N.F.N..
Here the results obtained with a further exposure of 0.34 ton x yr are
presented. They refer to two further annual cycles collected one before and one
after the first DAMA/LIBRA upgrade occurred on September/October 2008. The
cumulative exposure with those previously released by the former DAMA/NaI and
by DAMA/LIBRA is now 1.17 ton x yr, corresponding to 13 annual cycles. The data
further confirm the model independent evidence of the presence of Dark Matter
(DM) particles in the galactic halo on the basis of the DM annual modulation
signature (8.9 sigma C.L. for the cumulative exposure). In particular, with the
cumulative exposure the modulation amplitude of the single-hit events in the (2
-- 6) keV energy interval measured in NaI(Tl) target is (0.0116 +- 0.0013)
cpd/kg/keV; the measured phase is (146 +- 7) days and the measured period is
(0.999 +- 0.002) yr, values well in agreement with those expected for the DM
particles.Comment: presented at the Int. Conf. Beyond the Standard Models of Particle
Physics, Cosmology and Astrophysics (BEYOND 2010), 1-6 February 2010, Cape
Town, South Afric
Technical aspects in dark matter investigations
Some theoretical and experimental aspects regarding the direct dark matter
field are mentioned. In particular some arguments, which play a relevant role
in the evaluation of model dependent interpretations of experimental results
and in comparisons, are shortly addressed.Comment: Proceedings of TAUP 2011 Conferenc
Excluding Light Asymmetric Bosonic Dark Matter
We argue that current neutron star observations exclude asymmetric bosonic
non-interacting dark matter in the range from 2 keV to 16 GeV, including the
5-15 GeV range favored by DAMA and CoGeNT. If bosonic WIMPs are composite of
fermions, the same limits apply provided the compositeness scale is higher than
~10^12 GeV (for WIMP mass ~1 GeV). In case of repulsive self-interactions, we
exclude large range of WIMP masses and interaction cross sections which
complements the constraints imposed by observations of the Bullet Cluster.Comment: published versio
WIMPs search by scintillators: possible strategy for annual modulation search with large-mass highly-radiopure NaI(Tl)
The DAMA experiments are running deep underground in the Gran Sasso National
Laboratory. Several interesting results have been achieved so far. Here a
maximum likelihood method to search for the WIMP annual modulation signature is
discussed and applied to a set of preliminary test data collected with large
mass highly radiopure NaI(Tl) detectors. Various related technical arguments
are briefly addressed.Comment: 6 pages, 4 figures, LaTex. Contributed paper to TAUP97; to appear in
the Proceeding
Possible implications of the channeling effect in NaI(Tl) crystals
The channeling effect of low energy ions along the crystallographic axes and
planes of NaI(Tl) crystals is discussed in the framework of corollary
investigations on WIMP Dark Matter candidates. In fact, the modeling of this
existing effect implies a more complex evaluation of the luminosity yield for
low energy recoiling Na and I ions. In the present paper related
phenomenological arguments are developed and possible implications are
discussed at some extent.Comment: 16 pages, 10 figures, preprint ROM2F/2007/15, submitted for
publicatio
Observations of annual modulation in direct detection of relic particles and light neutralinos
The long-standing model-independent annual modulation effect measured by the
DAMA Collaboration, which fulfills all the requirements of a dark matter annual
modulation signature, and the new result by the CoGeNT experiment that shows a
similar behavior are comparatively examined under the hypothesis of a dark
matter candidate particle interacting with the detectors' nuclei by a coherent
elastic process. The ensuing physical regions in the plane of the dark
matter-particle mass versus the dark matter-particle nucleon cross-section are
derived for various galactic halo models and by taking into account the impact
of various experimental uncertainties. It is shown that the DAMA and the CoGeNT
regions agree well between each other and are well fitted by a supersymmetric
model with light neutralinos which satisfies all available experimental
constraints, including the most recent results from CMS and ATLAS at the CERN
Large Hadron Collider.Comment: 13 pages, 7 figure
DAMA annual modulation effect and asymmetric mirror matter
The long-standing model-independent annual modulation effect measured by DAMA
Collaboration is examined in the context of asymmetric mirror dark matter,
assuming that dark atoms interact with target nuclei in the detector via
kinetic mixing between mirror and ordinary photons, both being massless. The
relevant ranges for the kinetic mixing parameter are obtained taking into
account various existing uncertainties in nuclear and particle physics
quantities as well as characteristic density and velocity distributions of dark
matter in different halo models.Comment: 27 pages, 5 figures, 2 tables; version in publication on Eur. Phys.
J.
Model-independent Limits from Spin-dependent WIMP Dark Matter Experiments
Spin-dependent WIMP searches have traditionally presented results within an
odd group approximation and by suppressing one of the spin-dependent
interaction cross sections. We here elaborate on a model-independent analysis
in which spin-dependent interactions with both protons and neutrons are
simultaneously considered. Within this approach, equivalent current limits on
the WIMP-nucleon interaction at WIMP mass of 50 GeV/c are either
pb, pb or ,
depending on the choice of cross section or coupling strength
representation. These limits become less restrictive for either larger or
smaller masses; they are less restrictive than those from the traditional odd
group approximation regardless of WIMP mass. Combination of experimental
results are seen to produce significantly more restrictive limits than those
obtained from any single experiment. Experiments traditionally considered
spin-independent are moreover found to severely limit the spin-dependent phase
space. The extension of this analysis to the case of positive signal
experiments is explored.Comment: 12 pages, 12 figures, submitted to Phys. Rev.
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