Angular Distributions of 4.43-Mev Gamma Radiation fromC12(p, p′γ)C12

Abstract

The yield at 90 degrees, and 32 angular distributions of the 4.43-Mev gamma ray from the first-excited state of C/sup 12/ were measured for proton bombarding energies between 5 and 12 Mev. The excitation curve for inelastic scattering is characterized by a number of strong resonances, some of which were previously known. In addition, underlying the resonances, there is a monotonically rising background. The angular distributions were fitted by least squares to the expression W( THETA ) = A/sub o/ +A/sub 2/P/sub 2/(cos THETA ) + A/sub 4/Psub 4/(cos theta ). Those obtained tained in the region of the resonances at E/sub p = 5.36 Mev and E/sub p/ = 5.89 Mev can be interpreted by taking into account these two resonances with respective characters 3/2+ and 5/2+ plus one additional state at an excitation energy of 6.38 Mev (5/2+) in the compound nucleus N/sup 13/ which can be seen only in elastic scattering. A simple direct-reaction model using a nucleon-nucleon interaction accounts very well for four angular distributions at higher energies in regions showing no resonant structure. (auth)