Seasonal Changes of the ²¹⁴Po and ²¹³Po Half-Life Solar-Daily Variation Parameters

Results of a search for the masked regularities in the Po-214 alpha-active isotope half-life solardaily 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 similar to 2.9 x 10(-3) from the average daily value. Similar analysis of the Po-213 data collected in 2018-2022 years shows that amplitude of the deviation from the average value could reach similar to 3.8 x 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 Po-213 half-life which is tau(Po-213) = (3.6984 +/- 0.0006) mus was obtained on the base of the data collected during 2018-2022 years.