Search for rare processes with ZnWO4 crystal scintillators.

Radiopure ZnWO₄ crystal scintillators with mass (0.1-0.7 kg) have been developed and put in measurement in the Gran Sasso National Laboratories of the INFN to search for rare processes. The radioactive contamination of the crystals have been estimated and the double beta decay of zinc and tungsten isotopes was searched for, reaching a sensitivity at the level of 10¹⁸ - 10²¹ yr; in addition a new half-life limit on alpha transition of ¹⁸³W to the metastable excited level of ¹⁷⁹Hf has also been obtained. The achieved radiopurity of the ZnWO₄ crystals make them very promising detectors for ßß decay investigations while their anisotropic features make them very interesting detectors to investigate dark matter particles directionality. [ABSTRACT FROM AUTHOR]