Results from the latest run of the CRESST-II Dark Matter Search

by Dr Franz Pröbst

Tuesday 10 Jan 2012, 17:15 → 18:45 Europe/Berlin

MPP Hoersaal

CRESST-II is searching for Dark Matter WIMPs via elastic scattering off atomic nuclei in scintillating CaWO4 target crystals. CRESST has completed more than 730 kg days of data taking in 2011. The data collected with eight detector modules will be presented, each with a two-channel readout; one for a phonon signal and the other for the simultaneously produced scintillation light. The phonon channel provides a precise measurement of the energy deposited in the crystal by an interaction, while the ratio of scintillation light to deposited energy serves to distinguish possible signal events from the dominant backgrounds, and, to a certain extent also to determine the type of nucleus which was recoiling. 67 events are found in the acceptance region where a WIMP signal in the form of low energy nuclear recoils would be expected. We estimate background contributions to this observation using a maximum likelihood analysis, and find at a high statistical significance that these background sources alone are not sufficient to explain the data. The addition of a signal due to scattering of relatively light WIMPs could account for this discrepancy, and we determine the associated WIMP parameters.

Slides cresst.pdf