Seasonal Changes of the \({}^{{214}}\)Po and \({}^{{213}}\)Po Half-Life Solar-Daily Variation Parameters

Results of a search for the masked regularities in the \({}^{214}\)Po \(\alpha\)-active isotope half-life solar-daily variation parameters in the data collected during 2012–2015 years are presented. It is shown, that an amplitude of a sinusoidal function approximating half-life solar-daily dependence obtained by averaging data during 90 days for each season of the years could reach \({\sim}2.9\times 10^{-3}\) from the average daily value. Similar analysis of the \({}^{213}\)Po data collected in 2018–2022 years shows that amplitude of the deviation from the average value could reach \({\sim}3.8\times 10^{-3}\). This effect limits an accuracy of the high precision measurements with this or similar short-lived isotopes generating systematic errors if the data were collected during a relatively short time. The new value of the \({}^{213}\)Po half-life which is \(\tau(^{213}\)Po\()=(3.6984\pm 0.0006)mu\)s was obtained on the base of the data collected during 2018–2022 years.