Development of superconducting absorbers for CRESST light detectors

An important aspect of dark matter search experiments is the active background reduction by identification of the type of particle interacting in the detector. In CRESST this is achieved by a simultaneous detection of heat and light produced by an interaction in a scintillating crystal. The overall light collection efficiency is a crucial parameter in order to achieve enough sensitivity to measure the small fraction of the deposited energy that is emitted as scintillation light. For this purpose, a thin superconducting lead film deposited on sapphire substrates has been tested as an alternative light absorber to a silicon absorber. The first results already show a better light absorption of the lead film. Other superconducting films are also being analyzed.