RESONANT HEAVY-ION ELASTIC-SCATTERING FROM S-D SHELL NUCLEI

Angular distributions at angles 130°<θcm<180°have been measured for C12 + Si28, S32, Ca40 as well as Be9, C13 + Si28 in the energy range 20MeV<Ecm<35MeV. Cross sections rising towards 180°are observed for all reactions. Excitation functions for the back angle enhancement show distinct structures, most pronounced for C12 + Si28. Angular distributions for C12, especially those corresponding to peaks in the excitation function show oscillations of the type PJ2(cosθ). The C12 back angle enhancement decreases with target mass. Backscattering of the non-α nuclei Be9 and C13 is reduced by about two orders of magnitude in comparison with C12. Standard theoretical approaches fail to explain all the observed effects. NUCLEAR REACTIONS C12 + Si28, C12 + S32, C12 + Ca40, Be9 + Si28, C13 + Si28, measured σ (θ,E) elastic scattering, 130°<θc.m.<180°, 20MeV<Ec.m.<35MeV, deduced Jπ of resonances. © 1979 The American Physical Society.