Reaction Mechanism in Inelastic Scattering of Protons from Mg, Cr, and Other Elements from 3.5 to 7 Mev

Inelastic scattering of protons leading to the first excited states of ${\mathrm{Mg}}^{24}$ and ${\mathrm{Cr}}^{52}$ and to single excited states of other elements has been studied. $\frac{d\sigma }{d\omega }$ (90°) was measured as a function of proton energy from 3.5 to 7 Mev. Angular distributions of inelastically scattered protons and $p^{\prime }-\gamma$ angular correlations were taken at several energies. Experimental measurements are compared with direct-interaction theory and with predictions of the statistical model. Data for ${\mathrm{Cr}}^{52}(p, p^{\prime }){\mathrm{Cr}}^{52*}$ at 5.4 Mev is well fit by the statistical model. The ${\mathrm{Mg}}^{24}(p, p^{\prime }){\mathrm{Mg}}^{24*}$ reaction at 7 Mev can be interpreted as a direct interaction. The Mg reaction at 5.4 Mev and the Cr reaction at 7 Mev appear to have a bit of direct interaction in them. It is suggested that the amount of direct interaction in this ($p, p^{\prime }$) reaction depends on the nuclear barrier height. Statistical-model expressions for reactions studied are given in an Appendix.