K-shell internal-ionization probabilities in nuclearβ−decay

Total $K$-shell internal-ionization probabilities per ${\beta }^{-}$ decay of the isotopes ${}_{}{}^{63}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{143}{}_{}{}^{}\mathrm{Pr}$, and ${}_{}{}^{204}{}_{}{}^{}\mathrm{Tl}$ have been determined by x-ray spectroscopy with a high-energy-resolution Si(Li) detector. The number of emitted $K$ x rays was deduced in comparison to the absolute ${\beta }^{-}$-decay rate. The results of (4.6 ± 0.4) × ${10}^{-4\mathrm{}}$ for ${}_{}{}^{63}{}_{}{}^{}\mathrm{Ni}$, (2.92 ± 0.16) × ${10}^{-4\mathrm{}}$ for ${}_{}{}^{143}{}_{}{}^{}\mathrm{Pr}$, and (1.12 ± 0.11) × ${10}^{-4\mathrm{}}$ for ${}_{}{}^{204}{}_{}{}^{}\mathrm{Tl}$ are compared with previous experimental values and recent theoretical calculations of Law and Campbell. Good agreement is found between this theory and the present experimental results.