High-spin studies of fission products in fusion-evaporation reactions

Abstract

High-spin states of several isotopes in the mass A ≈ 100 region have been investigated following the fission of compound nuclei formed in three heavy-ion fusion-evaporation reactions. New sequences have been assigned to 91Sr, 107Ru, and 113, 115, 117, 119Cd isotopes using the complementary fission fragment technique. The ground-state bands have been extended to higher spins in 114, 116, 118, 120Cd. The level schemes of 88, 90, 92Sr and 101Tc have been considerably enriched. The plethora of results demonstrates the efficiency in which spectroscopic information can be collected on nuclei near the line of stability or slightly neutron-rich from studies of fission fragments following fusion-evaporation reactions. The prompt γ-ray intensity distributions of the fragments following the fission of the 197Pb compound nucleus are reported. The empirical distributions as a function of Z and A are not reproduced by expected yields of symmetric fission. Rather these distributions reflect the selectivity of Gammasphere to detect collective nuclei and to study high-spin excitations in fission fragments.