C. Bucci

Results from 730 kg days of the CRESST-II Dark Matter Search

The CRESST-II cryogenic Dark Matter search, aiming at detection of WIMPs via elastic scattering off nuclei in CaWO4 crystals, completed 730u2009kgu2009days of data taking in 2011. We present the data collected with eight detector modules, each with a two-channel readout; one for a phonon signal and the other for coincidently produced scintillation light. The former provides a precise measure of the energy deposited by an interaction, and the ratio of scintillation light to deposited energy can be used to discriminate different types of interacting particles and thus to distinguish possible signal events from the dominant backgrounds.Sixty-seven 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 from four sources: (1)xa0“leakage” from the e/γ-band (2)xa0“leakage” from the α-particle band (3)xa0neutrons and (4)xa0206Pb recoils from 210Po decay. Using a maximum likelihood analysis, we find, at a statistical significance of more than 4σ, that these 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.

Limits on WIMP dark matter using scintillating CaWO4 cryogenic detectors with active background suppression

We present first significant limits on WIMP dark matter by the phonon-light technique, where combined phonon and light signals from a scintillating cryogenic detector are used. Data from early 2004 with two 300xa0g CRESST-II prototype detector modules are presented, with a net exposure of 20.5xa0kg days. The modules consist of a CaWO4 scintillating “target” crystal and a smaller cryogenic light detector. The combination of phonon and light signals leads to a strong suppression of non-nuclear recoil backgrounds. Using this information to define an acceptance region for nuclear recoils we have 16 events from the two modules, corresponding to a rate for nuclear recoils between 12 and 40xa0keV of (0.87xa0±xa00.22) events/(kgxa0day). This is compatible with the rate expected from neutron background, and most of these events lie in the region of the phonon-light plane anticipated for neutron-induced recoils. A particularly strong limit for WIMPs with coherent scattering results from selecting a region of the phonon-light plane corresponding to tungsten recoils, where the best module shows zero events.

Limits on WIMP dark matter using sapphire cryogenic detectors

Abstract Data taken by CRESST with a cryogenic detector system based on 262 g sapphire crystals has been used to place limits on WIMP dark matter in the Galactic Halo. The experiment was especially sensitive for low-mass WIMPs with spin-dependent cross sections and improves on existing limits in this region.

Detection of the naturalαdecay of tungsten

The natural

Fracture Processes Observed with A Cryogenic Detector

ensuremath{alpha}

Energy-dependent light quenching in CaWO\(_4\) crystals at mK temperatures

-decay of

Discrimination of recoil backgrounds in scintillating calorimeters

^{180}mathrm{W}

Results on MeV-scale dark matter from a gram-scale cryogenic calorimeter operated above ground

has been unambiguously detected for the first time. The

Radiopurity of CaWO4 crystals for direct dark matter search with CRESST and EURECA

ensuremath{alpha}

Electron and gamma background in CRESST detectors

peak is found in a (