Multi-Quasiparticle States in Odd-Odd I-118

Abstract

The excited states of the doubly odd nucleus I-118 have been studied by using in-beam gamma-ray spectroscopy with the Cd-110(C-12, p3n) reaction at E-lab = 80 MeV. We have established several multi-quasi particle states associated with different proton and neutron quasiparticle configurations. A I-pi = 14(-) level at 2561 keV was newly observed and found to be associated with the pi h(11/2)nu d(5/2) configuration coupled to a pair of protons in the g(7/2) orbital. TRS calculations for the 14(-) level indicated a favored oblate state based on the fully aligned four-quasiparticle pi[h(11/2)(g(7/2))(2)](23/2)-nu[d(5/2)](5/2+) configuration. Another energetically favored state I-pi = 24(-) at 6216 keV could be interpreted as a noncollective oblate state from the fully aligned six-quasiparicle pi[h(11/2)(g(7/2))(2)](23/2)-nu[d(5/2)(h(11/2))(2)](25/2+) configuration. No Delta = 1 side band of the same parity as the pi h(11/2)nu h(11/2) band was observed while a side band built on the pi g(9/2 nu)h(11/2) configuration was considered to be caused by the gamma vibration coupling.