Acoustic spatial localization of events in superheated droplet detectors

We present a method for the spatial localization of bubble nucleation events in superheated droplet detectors. This is accomplished in a two step procedure: event validation and localization. Validation is accomplished through the application of signal processing techniques including wavelets, Chirp-Z transforms and pulse shape identification procedures, to the acoustical event record to filter out electromagnetic noise and background events which would otherwise be included in the spatial localization step. A 2D spatial localization is demonstrated using a common passive acoustic source localization technique with a 4 element microphone array, a simple generalized cross-correlation time delay of arrival algorithm, and a hot probe at known positions inside the detector. Results yield resolutions of ∼1.21 mm2 with a 90% confidence level.