Optimization of the readout electronics for a superheated superconducting granule particle detector

The sensitivity of Superheated Superconducting Granule (SSG) detectors is limited by the detectability of phase transition of single granules. The corresponding voltage pulse induced by the magnetic flux change in a pick-up coil was measured with an amplifier at room temperature. The readout circuit was optimized on the basis of a simple theoretical noise model, and a signal-to-noise ratio close to the expected theoretical limit was achieved. The minimal granule size required for a detectable signal has been determined as a function of the pick-up coil volume.