New development of radiopure ZnWO4 crystal scintillators

Abstract The residual radioactive contaminations of zinc tungstate crystal scintillators, produced by low-thermal-gradient Czochralski technique in various conditions, have been measured in the DAMA/R&D low background setup at the Gran Sasso National Laboratory (INFN, Italy). The total alpha activity has been measured in the detectors realized with different processes to vary between 158 and 1418 μ Bq/kg. The internal 228 Th contamination activity has been estimated as 0.34 μ Bq/kg in the most polluted crystal, while only upper limits for other ones have been set at level from μ Bq/kg to μ Bq/kg. These results open possibility for further radio-purifications of ZnWO 4 crystal scintillators, which are of potential interests in various fields.