Pulse Shape Analysis with Scintillating Bolometers

Among the detectors used for rare event searches, such as neutrinoless Double Beta Decay (0-DBD) and Dark Matter experiments, bolometers are very promising because of their favorable properties (excellent energy resolution, high detector efficiency, a wide choice of different materials used as absorber, . . .). However, up to now, the actual interesting possibility to identify the interacting particle, and thus to greatly reduce the background, can be fulfilled only with a double readout (i.e. the simultaneous and independent read out of heat and scintillation light or heat and ionization). This double read-out could greatly complicate the assembly of a huge, multi-detector array, such as CUORE and EURECA. The possibility to recognize the interacting particle through the shape of the thermal pulse is then clearly a very interesting opportunity. While detailed analyses of the signal time development in purely thermal detectors have not produced so far interesting results, similar analyses on macro-bolometers (∼10-500 g) built with scintillating crystals showed that it is possible to distinguish between an electron or x -ray and an α particle interaction (i.e. the main source of background for 0-DBD experiments based on the bolometric technique). Results on pulse shape analysis of a CaMoO4 crystal operated as bolometer are reported as an example. An explanation of this behavior, based on the energy partition in the heat and scintillation channels, is also presented. © Springer Science+Business Media, LLC 2012.