The electron capture decay of125I and145Pm

The productP K ω K of theK-capture probability and theK-fluorescence yieldω K was measured in the EC decay of 17.7 y145Pm and 60.14d125I by means ofK x-ray-γ-ray coincidences with semiconductor detectors. Accepting a best value ofω K =0.920 forZ=60 from the literature, values ofP K =0.606±0.025 and 0.554±0.025 for decay of145Pm to the 67.2 and 72.4 keV levels in145Nd, respectively, were determined, from which the application of EC theory givesQEC=153±4 keV to the ground state. TheP K ω K ratio to the 67.2 and 72.4 keV levels also was determined independently to be 1.11±0.01, which serves as a good check on theγ-ray-gatedP K values. Theγ-ray energies were determined more accurately to be 72.4±0.1 and 67.2±0.1 keV, together with a ratio of their relative intensities,I72.4/I67.2=3.35±0.09. In the decay of125I, a value ofP K ω K =0.699±0.030 was measured, and by using an independent determination ofQEC=178±2 keV to the ground-state from the literature, a value ofPK=0.801 is calculated from allowed EC theory, from whichω K =0.873±0.017 atZ=52 is obtained. This value is in good agreement with theoretical values and with a value of 0.875±0.028 predicted by the best fit curve of Bambyneket al.