## Abstract

The energy spectrum of 4$\cdot $5 MeV protons scattered by some light elements was determined by using a proportional counter in conjunction with absorbing foils. Magnesium gave groups attributed to levels at 1$\cdot $36 $\pm $ 0$\cdot $03 and 1$\cdot $82 $\pm $ 0$\cdot $04 MeV respectively above the ground state, the former being almost certainly associated with $^{24}$Mg. The angular distribution and excitation function of this group were examined in some detail. The proton groups from aluminium corresponded to levels at about 1 and 2$\cdot $15 $\pm $ 0$\cdot $05 MeV respectively above the ground state. The lower level has a complex structure and probably consists of two levels at about 0$\cdot $80 and 0$\cdot $97 $\pm $ 0$\cdot $02 MeV, the amplitudes of the corresponding proton groups showing a marked angular dependence. No inelastically scattered protons were observed from carbon, oxygen, or copper, while beryllium gave a group consistent with the existence of a metastable state in $^{9}$Be at 2$\cdot $39 $\pm $ 0$\cdot $05 MeV above the ground state. A short theoretical discussion of the mechanism of the process is given which suggests that inelastic scattering is predominantly a (p, p) process involving formation of a compound nucleus.