The European Underground Rare Event Calorimeter Array (EURECA) is a planned dark matter search experiment using cryogenic detectors and an absorber mass of up to 1 tonne. The project will be built in the Modane Underground Laboratory and will bring together researchers working on the CRESST and EDELWEISS experiments. EURECA featured prominently in the ASPERA road map of Astroparticle Physics experiments in Europe. Dark matter Dark matter is one of the significant unsolved problems in modern science. There is considerable evidence from astronomy and cosmology that a significant fraction of the mass of the Universe, and of galaxies is made up of non-luminous material. The nature of dark matter is currently unknown. However a popular hypothesis is that it consists of Weakly Interacting Massive Particles (WIMPs), particles with a large mass, but which only interact with ordinary matter through the weak nuclear force, so the majority that pass through the Earth do not hit a single atom. The aim of dark matter search experiments such as EURECA is to test this hypothesis by searching for WIMP dark matter interactions. WIMPs are predicted to exist by supersymmetry theory, which predicts a wide range of scattering cross-sections down to 10−10pb, corresponding to an interaction rate of ~1 event per year in a 1 tonne detector. Existing experiments such as CRESST and EDELWEISS have already ruled out higher interaction rates, but EURECA will search down to this lower limit. Cryogenic dark matter searches Cryogenic dark matter experiments use particle detectors operating at millikelvin temperatures to search for the elastic scattering of WIMPs of an atomic nuclei. A particle interaction inside an absorber crystal will create a large number of phonons, these thermalise inside a thermometer on the crystal surface, which records the rise in temperature. Such cryogenic detectors are used as they combine a high sensitivity with a low energy threshold and excellent resolution. Dark matter experiments are located in deep underground laboratories, and use extensive shielding to reduce the background radiation levels from cosmic rays. Early experiments were limited by the remaining background due to radioactive impurities close to the detectors. Therefore the second phase of CRESST and EDELWEISS used new detectors capable of distinguishing electron recoil events from nuclear recoils. Electron recoils are produced by alpha, beta and gamma particles which account for the vast majority of background events. WIMPs (and also neutrons) produce nuclear recoils. This is done by measuring