Search for non-Poissonian behavior in nuclear Β decay

We performed two independent counting experiments on a Β-emitting source of ₆₂¹⁵¹Sm by measuring the γ photon emitted in a fraction of the decays. For counting times ranging from 10^-3 to 5.12×10⁴ s, our measurements show no evidence of deviations from Poissonian behavior and, in particular, no sign of 1/f noise. These measurements put strong limits on non-Poissonian components of the fluctuations for the subset of decays accompanied by γ, and corresponding limits for the total number of Β decays. In particular, the magnitude of a hypothetical flicker floor is strongly bounded also for the Β decay. This result further constrains theories predicting anomalous fluctuations in nuclear decays.