K-Electron Ejection Accompanying NuclearKCapture

The momentum spectrum for the $K$ electrons ejected during allowed $K$ capture is calculated in the lowest order of perturbation theory using a nonrelativistic approximation for the electrons. The differences between this theory and the previously developed theory of Primakoff and Porter are pointed out. The new theory yields a spectrum which is virtually identical to the Primakoff-Porter spectrum over almost the entire momentum range of the ejected electrons. A discussion of relativistic effects and effects due to atomic screening and nuclear recoil is given. The discrepancies existing between the theoretical predictions and the experimental results are also discussed.