Disproof of solar influence on the decay rates of 90Sr/9090Sr/90Y

A custom-built liquid scintillation counter was used for long-term measurements of 90Sr/9090Sr/90Y sources. The detector system is equipped with an automated sample changer and three photomultiplier tubes, which makes the application of the triple-to-double coincidence ratio (TDCR) method possible. After decay correction, the measured decay rates were found to be stable and no annual oscillation could be observed. Thus, the findings of this work are in strong contradiction to those of Parkhomov (2011) who reported on annual oscillations when measuring 90Sr/9090Sr/90Y with a Geiger–Müller counter. Sturrock et al. (2012) carried out a more detailed analysis of the experimental data from Parkhomov and claimed to have found correlations between the decay rates and processes inside the Sun. These findings are questionable, since they are based on inappropriate experimental data as is demonstrated in this work. A frequency analysis of our activity data does not show any significant periodicity.