Inelastic scattering of 100 MeV protons from 12C using a Ge(Li) total-absorption proton counter

Abstract

A cooled Ge(Li) detector has been used as a total-absorption proton counter for the energy analysis of 100 MeV protons scattered from a target of natural carbon. An overall energy resolution of 0.5 MeV to 0.6 MeV (FWHM) was achieved. The differential cross sections for the excitation of the 4.43, 7.66, 9.64, 10.8, 11.8, 12.7, 14.1, 15.1, and 16.1 MeV levels have been measured at nine angles from 10 to 60° (lab). The angular distributions for the 10.8, 11.8, and 14.1 MeV levels represent the first measured proton-scattering data for these levels in the intermediate energy region (> 50 MeV). A qualitative discussion of the excited states is presented, based mainly on the shapes of the angular distributions. At large scattering angles (> 30°), the angular distribution for the 0+ level at 7.66 MeV deviates significantly from 0+ angular distributions measured in 24Mg and 28Si, suggesting different mechanisms of excitation of 0+ states in the p and s–d shells.