Gamma Rays from the Proton Bombardment of 24Mg, 25Mg and 26Mg

Abstract

The gamma rays following the inelastic scattering of protons by Mg/sup 24/, Mg/sup 25/, and Mg/sup 26/ were investigated at proton energies up to 5.7 Mev. The energy spectrbea of the gamma-rays at several protoin energies have been obtained for each isotope. 2/sup +/ was assigned to the second, third, and fourth excited level of Mg/sup 26/ considering the gamma-ray branching ratios for those levels. The yields of gamma rays from the first excited levels were found to have peaks at proton energies of 4.0, 4.6 and 5.05 Mev for Mg/sup 24/ (p,p' gamma ) reaction and 4.9 and 5.4 Mev for Mg/sup 24/ (p,p' gamma ) reaction, respectively. These resonances correspond to the levels at 8.1, 0.7 and 7.14 Mev for Al/sup 25/, and 13.0 and l5.5 Mev for Al/sup 27/. To determine the spins for those levels, angular distributions were measured at rescnance energies. Spin values of 3/2 and 5/2 are probable for 7.l4 Mev level in Al/sup 25/ and 13.0 Mev level in Al/sup 27k/, respectively. For the 13.5 Mev level in Al/sup 27/, the spin of 3/2 is also Probable, but 5/2 can not be excluded because of tbe presence of the cascade gamma rays frommore » higher levels. The tetal cross sections for the gamma-ray emission are estimated to be about 700 mb at 5.05 Mev resonance for Mg/ sup 24/ and a few hundred mb for the 4.9 and 5.4 Mev resonances for Mg/sup 26/. (auth)« less