Inner-Shell Ionization in the K-Electron Capture Decay of TUNGSTEN-181.

The probability P(,KK) of double K-shell vacancy production during K-electron capture in the ('181)W to ('181)Ta transition is measured to be (1.25 (+OR-) 0.42) x 10('-5) by observing Ta. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). in coincidence with Ta K x rays using high resolution semiconductor detectors. This value is found to be in agreement with the estimate made using Intemann's theoretical calculation of the K-electron ejection probability, P(,ej), and Mukoyama's ratio of the probabilities for excitation and ejection, P(,ex)/P(,ej). The energy shift of the Ta. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). with respect to the normal Ta K(alpha)(,1) x ray is found to be 1085 (+OR-) 70 eV. The probabilities of K-electron capture in the decay of ('181)W to the levels at 136.3 and 158.7 keV are found to be 0.152 (+OR-) 0.086 and 0.090 (+OR-) 0.028 respectively.