Search for Variations of 213Po Half-Life

A device with the parent Th-229 source was constructed to search for variations of the daughter Po-213 half-life (T (1/2) = 4.2 mu s). A solar-daily variation with amplitude A (So) = (5.3 +/- 1.1) x 10(-4), a lunar-daily variation with amplitude A (L) = (4.8 +/- 2.1) x 10(-4), and a sidereal-daily variation with amplitude A (S) = (4.2 +/- 1.7) x 10(-4) were found upon proceeding the data series over a 622-day interval (from July 2015 to March 2017). The Po-213 half-life mean value is found to be T (1/2) = 3.705 +/- 0.001 mu s. The reference value is corrected by 12%.