On the absence of appreciable half-life changes in alpha emitters cooled in metals to 1 Kelvin and below

Abstract

The recent suggestion that dramatic changes may occur in the lifetime of alpha and beta decay when the activity, in a pure metal host, is cooled to a few Kelvin, is examined in the light of published low temperature nuclear orientation (LTNO) experiments on such sources cooled to as low as 25 mK, with emphasis here on alpha decay. In LTNO observations are made of the anisotropy of radioactive emissions with respect to an axis of orientation. Correction of data for decay of activities in metallic samples held at temperatures at and below 1 Kelvin for periods of several days has been a routine element of LTNO experiments for many years. No evidence for any change of half-life on cooling, with an upper level of order 1%, has been found, in striking contrast to the predicted changes, for alpha decay, of several orders of magnitude. The proposal that such dramatic changes might alleviate problems of disposal of long-lived radioactive waste is shown to be unrealistic.