WARP liquid argon detector for dark matter survey

The WARP programme is a graded programme intended to search for cold dark matter in the form of weakly interacting massive particles. These particles may produce via weak interactions nuclear recoils in the energy range 10-100 keV. A cryogenic noble liquid like argon, already used in the realization of very large detector, permits the simultaneous detection of both ionization and scintillation induced by an interaction, suggesting the possibility of discriminating between nuclear recoils and electrons mediated events. A 2.3 l two-phase argon detector prototype has been used to perform several tests on the proposed technique. Next step is the construction of a 100 l sensitive volume device with potential sensitivity a factor 100 better than presently existing experiments.