The CRESST-III low-mass WIMP detector

The next generation direct dark matter experiment CRESST-III has a high potential to significantly increase the sensitivity to low-mass WIMPs (m(x) less than or similar to 10 GeV/c(2)). We present the new CRESST detector module: it consists of a 24g CaWO4 crystal operated as a phonon detector and a 20x20 mm(2) silicon-on-sapphire light detector. The phonon energy threshold is lowered to similar to 100 eV and a light detector resolution of typically 5 eV is achieved. A fully-scintillating inner detector housing is realised which efficiently rejects events from surface alpha decays. The CaWO4 sticks holding the target crystal are also operated as calorimeters to discriminate all possible artefacts related to the support structure. A projection for the sensitivity to spin-independent WIMP-nucleon scattering is given for the first phase of CRESST-III which will start beginning of 2016.