Seasonal variations of decay rate measurement data and their interpretation.

Measurement data of long-lived radionuclides, for example, (85)Kr, (90)Sr, (108m)Ag, (133)Ba, (152)Eu, (154)Eu and (226)Ra, and particularly the relative residuals of fitted raw data from current measurements of ionization chambers for half-life determination show small periodic seasonal variations with amplitudes of about 0.15%. The interpretation of these fluctuations is a matter of controversy whether the observed effect is produced by some interaction with the radionuclides themselves or is an artifact of the measuring chain.