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Sturrock et al. have published a “rebuttal” to a paper by Pomme et al. who refuted their claim that variations in a radon decay experiment at the Geological Survey of Israel (GSI) can be associated with solar rotation. Sturrock et al. misinterpret the variability of the decay rates in the gamma counter to assert influences by solar and cosmic neutrinos on beta decay and draw unsubstantiated conclusions about solar dynamics. Evidence suggests that the radon measurements were susceptible to solar irradiance and rainfall, whereas there is no indication that radioactive decay is influenced by the solar neutrino flux. In this reply to the rebuttal, the arguments raised by Sturrock et al. are scrutinised.

Claims were made by Sturrock et al. that radioactive decay can be induced by interaction of the nucleus with solar neutrinos and that cyclic modulations in decay rates are indicative of the dynamics of the solar interior. They analysed a series of measurements of gamma radiation associated with the emanation and decay of radon in a sealed container at the Geological Survey of Israel (GSI) laboratory. The integral count rates in the NaI detector showed strong variations in time of year and time of day. From time-series analysis, Sturrock et al. claim the presence of small oscillations at frequencies in a range between 7.4 a−1 and 12.5 a−1, which they speculatively associated with rotational influence on the solar neutrino flux. In this work, it is argued that the GSI radon measurements are unsuited for studying the variability of decay constants, because the data are strongly influenced by environmental conditions, such as solar irradiance and rainfall. At the JRC and PTB, decay rate measurements of the radon decay chain were performed with ionisation chambers, gamma-ray spectrometers and an alpha spectrometer. No deviation from the exponential-decay law was observed. The existence of cyclic variations in the decay constants is refuted, as well as the concept of measuring solar rotation through radioactive decay.