Radiopurity of $ZnWO_4$ Crystal Scintillators

Recently $ZnWO_4$ was proposed as perspective material for low-counting experiments to search for rare processes. Such experiments demand high radiopurity of $ZnWO_4$ crystal scintillators. With this aim radioactive contamination of large volume (0.1-0.7 kg) $ZnWO_4$ crystal scintillators were measured in the underground Laboratori Nazionali del Gran Sasso of the INFN at the depth of ≈ 3600 m water equivalent.