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Up to now there are no clear evidences for an observation of dark matter. Thus, to improve the sensitivity of future experiments, among other things, the active detector mass has to be improved.
The CRESST collaboration and the EDELWEISS (Expérience Pour Détecter Les WIMPs En Site Souterrain) collaboration have joined forces to build the EURECA (European Underground Rare Event Calorimeter Array) experiment with an active detector mass of about one ton.
Both, calcium tungstate and germanium are used in the EURECA experiment. For calcium tungstate the same detection technique is used as for CRESST detectors. The detection technique from the EDELWEISS experiment is used for germanium. Unlike calcium tungstate germanium is not scintillating. However, since germanium is a semi conductor, energy depositions are leading to a rise in temperature as well as ionization. The strength of the ionization signal depends also on the type of the incident particle. Thus, the distinction between background events and WIMP interactions is achieved via a simultaneously read out of the temperature rise and the ionization generated by an energy deposition.
Due to the use of different detector materials as well as different detection techniques in one setup, systematical uncertainties for the direct search for dark matter are strongly reduced. In addition to the large active detector mass this reduction of systematical uncertainties is one of the advantages of the EURECA experiment.