Atomic Electron Correlation in Nuclear Electron Capture

The effect of electron-electron Coulomb correlation on orbital-electron capture by the nucleus has been treated by the multiconfigurational Hartree-Fock approach. The theoretical ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ $\frac{L}{K}$ capture ratio is found to be 0.086, and the ${}_{}{}^{37}{}_{}{}^{}\mathrm{Ar}$ $\frac{M}{L}$ ratio, 0.102. Both ratios are smaller than the independent-particle predictions. Measurements exist for the Ar $\frac{M}{L}$ ratio, and agreement between theory and experiment is excellent.