Calculation of fractional electron capture probabilities

A “Table of Radionuclides” is being prepared which will supersede the “Table de Radionucléides” formerly issued by the LMRI/LPRI (France). In this effort it is desirable to have a uniform basis for calculating theoretical values of fractional electron capture probabilities. A table has been compiled which allows one to calculate conveniently and quickly the fractional probabilities PK, PL, PM, PN and PO, their ratios and the assigned uncertainties for allowed and non-unique first forbidden electron capture transitions of known transition energy for radionuclides with atomic numbers from Z=3 to 102. These results have been applied to a total of 28 transitions of 14 radionuclides (7Be, 22Na, 51Cr, 54Mn, 55Fe, 68Ge, 68Ga, 75Se, 109Cd, 125I, 139Ce, 169Yb, 197Hg, 202Tl). The values are in reasonable agreement with measured values. The relative standard uncertainty of the values for PK is estimated to be generally smaller than 0.3% and smaller than 3% for PL.