Improvement of radiopurity level of enriched $^{116}$CdWO$_4$ and ZnWO$_4$ crystal scintillators by recrystallization
physics.ins-det
/ Authors
A. S. Barabash, P. Belli, R. Bernabei, Yu. A. Borovlev, F. Cappella, V. Caracciolo, R. Cerulli, F. A. Danevich, A. Incicchitti, V. V. Kobychev
and 10 more authors
S. I. Konovalov, M. Laubenstein, V. M. Mokina, O. G. Polischuk, O. E. Safonova, V. N. Shlegel, V. I. Tretyak, I. A. Tupitsyna, V. I. Umatov, V. N. Zhdankov
/ Abstract
As low as possible radioactive contamination of a detector plays a crucial role to improve sensitivity of a double beta decay experiment. The radioactive contamination of a sample of $^{116}$CdWO$_4$ crystal scintillator by thorium was reduced by a factor $\approx 10$, down to the level 0.01 mBq/kg ($^{228}$Th), by exploiting the recrystallization procedure. The total alpha activity of uranium and thorium daughters was reduced by a factor $\approx 3$, down to 1.6 mBq/kg. No change in the specific activity (the total $α$ activity and $^{228}$Th) was observed in a sample of ZnWO$_4$ crystal produced by recrystallization after removing $\approx 0.4$ mm surface layer of the crystal.