SUPERHEATED LIQUID DETECTORS
The superheated liquid detectors developed by our group were upgraded for the IVth 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 5-12oC evidenced a dependence of the event rate with the droplet sizes, in model agreement for temperatures below 8oC. 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.