Series array of superconducting tunnel junctions as phonon sensor in a dark matter detector

A design of a cryogenic detector for a WIMP dark matter search based on a single crystal absorber using Series Array of Superconducting Tunnel Junctions (SASTJs) as readout sensors has been presented. In order to investigate the behaviour of such a detector the response of two spatially separated Series Arrays of Superconducting Tunnel Junctions (SASTJs) to the non-equilibrium phonons generated in a single crystal of BaF2, by external alpha-particles has been measured. A strong position dependence in pulse height and pulse shape of the detector response has been observed. The fast time response of the SASTJs permits time resolved measurements of the spatially separated particle interactions in the crystal.