Showing papers by "Claude Leroy published in 2006"

The PICASSO Direct Dark Matter Search Experiment

Abstract: The PICASSO experiment is searching for cold dark matter through the direct detection of weakly interacting massive particles (WIMPs), in particular neutralinos (χ) via their spin‐dependent interactions with nuclei. The experiment is installed in the Sudbury Neutrino Observatory Laboratory at a depth of 2070 m (6000 mwe). PICASSO makes use of the superheated droplet technique with C4F10 as the active material, and searches for χ interactions on 19F. The results of these measurements are presented in terms of limits on the spin‐dependent χ‐proton and χ‐neutron cross sections. Limits on the effective χ‐proton and χ‐neutron coupling strengths ap and an are also reported. The results exclude new regions of the spin‐dependent χ‐nucleon interaction parameter space. The next phase of PICASSO is briefly discussed.

Simulation of special bubble detectors for PICASSO.

Abstract: 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 polymerised 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.

Direct dark matter search using large-mass superheated droplet detectors in the PICASSO experiment.

Abstract: The PICASSO experiment investigates the presence and nature of dark matter in the Universe. The experiment is based on the detection of acoustic signals generated in explosive phase transitions induced by dark matter particles. This technique is an alternative more traditional detection technique like scintillation and ionisation, which are largely employed for dark matter search. One of the main advantages of this technique, besides its sensitivity to very low nuclear recoil energies (few keV), is its excellent background suppression features. A pilot experiment consisting of six superheated droplet detectors (40 g of active mass) is presently taking data at the Sudbury Neutrino Observatory (SNO) at a depth of 2000 m. We discuss the operation, calibration and data acquisition of the experiment and also the ongoing work to increase the sensitivity and the active mass of the detectors.