Radioactive Core Ions Of Microclusters, ''Snowballs'' In Superfluid Helium

Short-lived beta-ray emitters, B-12, sustaining nuclear spin polarization were introduced into superfluid helium. The nuclear polarization of B-12 was observed via measurement of beta-ray asymmetry. It was found that the nuclear polarization was preserved throughout the lifetime of B-12 (20.3 ms). This suggests that the ''snowball'', an aggregation of helium atoms produced around an alien ion, constitutes a suitable milieu for freezing-out the nuclear spin of the core ion and that most likely the solidification takes place at the interior of the aggregation.