Cosmology, dark matter and the PICASSO Project

Remarkable progress has been made in both observational and theoretical cosmology, leading to the LCDM model, attributing 30% of the total Universe density to gravitational matter, and 70% to the so-called dark energy. About 1-2% of the matter is presently visible, the rest being composed of baryonic dark matter (DM), neutrinos and non-baryonic DM. The presence of neutralinos in halos around galaxies could solve the DM problem, and also support the SUSY extension of the Standard Model. Many detectors with extremely low backgrounds aim at its detection. One of these, the PICASSO Project, uses the technology of the bubble chamber. Substantial progress in the past year gives us confidence that this technique may lead to a detector with largely improved sensitivity to explore spin-dependent neutralino interaction. A new detector with increased mass is under construction for an experiment to be deployed in the underground laboratory of SNO.