13 research outputs found
Determining Ratios of WIMP-Nucleon Cross Sections from Direct Dark Matter Detection Data
Weakly Interacting Massive Particles (WIMPs) are one of the leading
candidates for Dark Matter. So far the usual procedure for constraining the
WIMP-nucleon cross sections in direct Dark Matter detection experiments have
been to fit the predicted event rate based on some model(s) of the Galactic
halo and of WIMPs to experimental data. One has to assume whether the
spin-independent (SI) or the spin-dependent (SD) WIMP-nucleus interaction
dominates, and results of such data analyses are also expressed as functions of
the as yet unknown WIMP mass. In this article, I introduce methods for
extracting information on the WIMP-nucleon cross sections by considering a
general combination of the SI and SD interactions. Neither prior knowledge
about the local density and the velocity distribution of halo WIMPs nor about
their mass is needed. Assuming that an exponential-like shape of the recoil
spectrum is confirmed from experimental data, the required information are only
the measured recoil energies (in low energy ranges) and the number of events in
the first energy bin from two or more experiments.Comment: 33 pages, 20 eps figures; v2: typos fixed, references added and
updated, revised version for publicatio
Probing the Local Velocity Distribution of WIMP Dark Matter with Directional Detectors
We explore the ability of directional nuclear-recoil detectors to constrain
the local velocity distribution of weakly interacting massive particle (WIMP)
dark matter by performing Bayesian parameter estimation on simulated
recoil-event data sets. We discuss in detail how directional information, when
combined with measurements of the recoil-energy spectrum, helps break
degeneracies in the velocity-distribution parameters. We also consider the
possibility that velocity structures such as cold tidal streams or a dark disk
may also be present in addition to the Galactic halo. Assuming a
carbon-tetrafluoride detector with a 30-kg-yr exposure, a 50-GeV WIMP mass, and
a WIMP-nucleon spin-dependent cross-section of 0.001 pb, we show that the
properties of a cold tidal stream may be well constrained. However, measurement
of the parameters of a dark-disk component with a low lag speed of ~50 km/s may
be challenging unless energy thresholds are improved.Comment: 38 pages, 15 figure
Simulation of Special Bubble Detectors for PICASSO
The PICASSO project is a cold dark matter (CDM) search experiment relying on
the superheated droplet technique. The detectors use superheated freon liquid
droplets (active material) dispersed and trapped in a polymerized gel. This
detection technique is based on the phase transition of superheated droplets at
about room temperature and ambient pressure. The phase transition is induced by
nuclear recoils when an atomic nucleus in the droplets interacts with incoming
subatomic particles. This includes CDM particles candidate as the neutralino (a
yet-to-discover particle predicted in extensions of the Standard Model of
particle physics). Simulations performed to understand the detector response to
neutrons and alpha particles are presented along with corresponding data
obtained at the Montreal Laboratory.Comment: 13 pages, 4 figures. To appear in the Proceedings of the 14th
International Conference on Solid State Dosimetry, June 27 - July 2 2004,
Yale University, New Haven, CT, US
The and sensitivities of the SPL-Fréjus project revisited
Submitted to Eur. Phys. J. CAn optimization of the CERN SPL beam line has been performed guided by the sensitivities to the \theta_{13} mixing angle and to the \delta_{CP} Dirac CP violating phase. A UNO-like 440 ktons water Cerenkov detector located at 130 km from the target in a new foreseen Frejus laboratory has been used as a generic detector. Concerning the \delta_{CP} independent \theta_{13} sensitivity, a gain of about 20% may be reached using a 3.5 GeV proton beam with a 40 m long, 2 m radius decay tunnel compared to the up to now considered 2.2 GeV beam energy and 20 m long, 1 m radius decay tunnel. This may motivate new machine developments to upgrade the nominal SPL proton beam energy
Searches for monojets and monophotons with the ATLAS detector
Studies of events with a single high energy jet or photon, and large missing transverse momentum at the Large Hadron Collider is one of the most effective ways to search for physics beyond the Standard Model. The background from the Standard Model processes is dominated by jet/photon production associated with Z or W bosons undergoing leptonic decays to neutrinos and/or unidentified electrons or muons. The sensitivity to new physics signals relies on the good understanding and the accurate estimation of these backgrounds, and therefore the use of data-driven techniques is often required. In this article, I will present a compilation of the latest results from the monojet and monophoton searches based on the analysis of the 2011 and 2012 proton-proton collision data collected with the ATLAS detector at a center-of-mass energy of 7 TeV and 8 TeV, respectively. The results are interpreted in the context of various models beyond the Standard Model including large extra dimensions, gauge mediated supersymmetry breaking and effective field theory of dark matter production