SUPERHEATED LIQUID DETECTORS

The superheated liquid detectors developed by our group were upgraded for the IV^th phase of the SIMPLE dark matter search, and exploited towards novel applications in alpha particle detection. Developments of the SIMPLE bubble chamber aiming at a 10³ sensitivity improvement comprise a new hydrophone-based acoustic instrumentation and an integrated frequency-based analysis capable of discriminating signal events from acoustic background. The alpha-droplet interaction within superheated droplet detectors (SDD) was examined via computational studies, and a geometric model developed to describe the detector response. Experiments with U and Sm-doped SDDs at 5-12^oC evidenced a dependence of the event rate with the droplet sizes, in model agreement for temperatures below 8^oC. Above higher temperature, the increasing bubble population yields an acoustic sensitivity loss that, once corrected by attenuation coefficient, restored the agreement with experiment. The results suggest the viability of a SDD-based alpha spectrometer using mono-sized droplets.