FLUCTUATIONS IN RADIOACTIVE DECAYS .2. EXPERIMENTAL RESULTS

We experimentally investigate the decay statistics of a gamma source o f Sn-119m(50). We find that, for counting periods of the order of 10 h , the variance is higher than the Poissonian value by more than one or der of magnitude. A careful study of the relative Allan variance and t he measurement of the generalized Allan variance demonstrates that the observed anomaly is not caused by 1/f noise. Rather, even if counting periods are much shorter than the nucleus lifetime, the variance exce ss is a consequence of the nonequilibrium nature of the decay process. This conclusion is supported by the quantitative agreement between ou r experimental data and the theoretical formulas derived in the preced ing paper.