CdWO4 scintillating bolometer for Double Beta Decay: Light and heat anticorrelation, light yield and quenching factors

We report the performances of a 0.51 kg CdWO4 scintillating bolometer to be used for future Double Beta Decay Experiments. The simultaneous readout of the heat and the scintillation light allows to discriminate between different interacting particles aiming at the disentanglement and the reduction of background contribution, key issue for next generation experiments. We will describe the observed anticorrelation between the heat and the light signal and we will show how this feature can be used in order to increase the energy resolution of the bolometer over the entire energy spectrum, improving up to a factor 2.6 on the 2615 key line of (TI)-T-208. The detector was tested in a 433 h background measurement that permitted to estimate extremely low internal trace contaminations of Th-232 and U-238. The light yield gamma/beta, alpha's and neutrons is presented. Furthermore we developed a method in order to correctly evaluate the absolute thermal quenching factor of alpha-particles in scintillating bolometers. (C) 2010 Elsevier B.V. All rights reserved.