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 36 Cl and 32 Si, acquired at the Brookhaven National Laboratory (BNL), to search for evidence that might be indicative of a process involving 252 P.A. Sturrock et al. 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 226 Ra 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.

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We provide the results from a spectral analysis of nuclear decay data displaying annually varying periodic fluctuations. The analyzed data were obtained from three distinct data sets: 32 Si and 36 Cl decays reported by an experiment performed at the Brookhaven National Laboratory (BNL), 56 Mn decay reported by the Children's Nutrition Research Center (CNRC), but also performed at BNL, and 226 Ra decay reported by an experiment performed at the Physikalisch-Technische-Bundesanstalt (PTB) in Germany. All three data sets exhibit the same primary frequency mode consisting of an annual period. Additional spectral comparisons of the data to local ambient temperature, atmospheric pressure, relative humidity, Earth-Sun distance, and their reciprocals were performed. No common phases were found between the factors investigated and those exhibited by the nuclear decay data. This suggests that either a combination of factors was responsible, or that, if it was a single factor, its effects on the decay rate experiments are not a direct synchronous modulation. We conclude that the annual periodicity in these data sets is a real effect, but that further study involving additional carefully controlled experiments will be needed to establish its origin.

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Evidence for an anomalous annual periodicity in certain nuclear decay data has led to speculation concerning a possible solar influence on nuclear processes. As a test of this hypothesis, we here search for evidence in decay data that might be indicative of a process involving solar rotation, focusing on data for 32 Si and 36 Cl decay rates acquired at the Brookhaven National Laboratory. Examination of the power spectrum over a range of frequencies (10 -15 year -1 ) appropriate for solar synodic rotation rates reveals several periodicities, the most prominent being one at 11.18 year -1 with power 20.76. We evaluate the significance of this peak in terms of the false-alarm probability, by means of the shuffle test, and also by means of a new test (the "shake" test) that involves small random time displacements. The last two tests are the more robust, and indicate that the peak at 11.18 year -1 would arise by chance only once out of about 10 7 trials. However, the fact that there are several peaks in the rotational search band suggests that modulation of the count rate involves several low-Q oscillations rather than a single high-Q oscillation, possibly indicative of a partly stochastic process. To pursue this possibility, we investigate the running mean of the power spectrum, and identify a major peak at 11.93 year -1 with peak running-mean power 4.08. Application of the shuffle test indicates that there is less than one chance in 10 11 of finding by chance a value as large as 4.08.Application of the shake test leads to a more restrictive result that there is less than one chance in 10 15 of finding by chance a value as large as 4.08. We find that there is notable agreement in the running-mean power spectra in the rotational search band formed from BNL data and from ACRIM total solar irradiance data. Since rotation rate estimates derived from irradiance data have been found to be closely related to rotation rate estimates derived from low-energy solar-neutrino data, this result supports the recent conjecture that solar neutrinos may be responsible for variations in nuclear decay rates.We also carry out a similar comparison with local temperature measurements, but find no similarity between power spectra formed from BNL measurements and from local temperature measurements.3/31