Excitation Potentials and Shell Corrections for the ElementsZ2=20toZ2=30

Abstract

Excitation potentials and shell corrections for the elements ${Z}_{2}=20$ to ${Z}_{2}=30$ are evaluated from experimental stopping-power data for 5-12-MeV protons and deuterons. Use is made of Walske's $K$- and $L$-shell corrections and shell corrections calculated by Bonderup on the basis of the Thomas-Fermi model. It is suggested that Cu be used rather than Al as a standard for stopping-power measurements. ${I}_{\mathrm{Cu}}$ is deduced to be 320.8\ifmmode\pm\else\textpm\fi{}3.8 eV. Relative stopping-power measurements by Bakker and Segr\`e, by Teasdale, by Burkig et al., and by Nakano et al. are normalized to Cu, and mean excitation potentials are found by means of Bonderup's shell corrections. With only a few exceptions, they agree with the $I$ values obtained from our measurements. Within the ${Z}_{2}$ interval treated here, it is found that $\frac{I}{{Z}_{2}}$ increases with increasing ${Z}_{2}$, contrary to the general trend through the periodic system of elements.