Resonant octupole strength at 13 MeVin (58)Ni and (60)Ni and the character of the 53A(-1/3) state in heavy nuclei

Inelastic electron scattering reveals a concentration of resonant E3 strength at (13.3 ± 0.2) MeV in 51Ni and (12.8 ± 0.2) MeV in 60Ni. The energy agrees closely with the 52 A- 1/ ' MeV predicted by Hamamoto for the isovector (1 hwl E3 mode on the basis of the Bohr-Mottelson self-consistent shell model, but the strength, (13 ± 1)% and (8 ± 2)% of the energy weighted sum rule, respectively, is a factor of 5 too large. This result weakens recent arguments in favor of a monopole assignment for the 53 A-i/ 3 MeV resonance found by (e,e'l in heavy nuclei.National Science FoundationNaval Postgraduate School Foundatio

Comparison of giant multipole resonances of multipolarity E1 to E4 in (58)Ni (T(0) = 1) and (60)Ni (T(0) = 2) with inelastic electron scattering

The cross section for electron scattering from the isotopes (58)Ni and (60)Ni has been measured with electrons of 103 MeV at scattering angles of 45, 60,75, and 105° between 3 and 50 MeV excitation energy. Resonances or resonancelike structures at approximate excitation energies of (7-8) MeV, 13 MeV, (16-17) MeV, (18-19) MeV, 27 MeV, 32 MeV, and 40 MeV were classified on the basis of their momentum transfer dependence and discussed in the framework of the shell model. Difficulties in the extraction of the cross section and model dependencies of the interpretation are discussed.Research supported in part by the National Science Foundation and the Naval Postgraduate School Research FoundationApproved for public release; distribution is unlimited