Power Spectrum Analysis of Physikalisch-Technische Bundesanstalt Decay-Rate Data: Evidence for Solar Rotational Modulation

Evidence for an anomalous annual periodicity in certain nuclear-decay data has led to speculation on a possible solar influence on nuclear processes. We have recently analyzed data concerning the decay rates of Cl-36 and Si-32, acquired at the Brookhaven National Laboratory (BNL), to search for evidence that might be indicative of a process involving solar rotation. Smoothing of the power spectrum by weighted-running-mean analysis leads to a significant peak at frequency 11.18 year(-1), which is lower than the equatorial synodic rotation rates of the convection and radiative zones. This article concerns measurements of the decay rates of Ra-226 acquired at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. We find that a similar (but not identical) analysis yields a significant peak in the PTB dataset at frequency 11.21 year(-1), and a peak in the BNL dataset at 11.25 year(-1). The change in the BNL result is not significant, since the uncertainties in the BNL and PTB analyses are estimated to be 0.13 year(-1) and 0.07 year(-1), respectively. Combining the two running means by forming the joint power statistic leads to a highly significant peak at frequency 11.23 year(-1). We will briefly comment on the possible implications of these results for solar physics and for particle physics.