Direct Dark Matter Search with CRESST-II: Results from 730kg-days
Dr. Jean-Côme Lanfranchi (TU München, Garching)

CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) is an experiment aimed at the direct detection of Dark Matter. The experiment uses scintillating CaWO4 single crystals operated at mK-temperatures to measure the recoil energy deposited by elastic WIMP (Weakly Interacting Massive Particle) nucleon scattering. By recording the heat as well as the associated scintillation light generated by an energy deposition in the crystal, CRESST is able to achieve a unique discrimination on an event-by-event level. After a two-year measuring campaign CRESST II has now gathered 730kg days of data. In the analyzed data set a total of 67 events in the region of interest have passed all cuts and are difficult to explain with contributions from common backgrounds such as alpha-, beta-, gamma-radiation or neutrons. In a dedicated likelihood analysis it could be demonstrated that these backgrounds alone are not sufficient to account for the events observed. However, the addit! ion of a signal induced by a relatively light WIMP could explain the observed discrepancy – the associated parameters for such a Dark Matter particle will be discussed. The talk will conclude on future steps to be taken to clarify the present situation.