Multi-quasiparticle isomers involving proton-particle and neutron-hole configurations in ~(131)I and ~(133)I

摘要

The nuclei ~(131)I and ~(133)I have been populated in multi-nucleon transfer reactions between ~(136)Xe ions and various targets, and their structure investigated by time-correlated γ-ray coincidence spectroscopy and the measurement of γ-ray angular correlations. A 19/2~- isomer at 1918 keV, with a half-life of 24(1) s, has been identified in ~(131)I, as well as nanosecond isomers with J~π = 23/2~+ in both isotopes. A T_(1/2) = 25(3) ns isomer at 4308 keV in ~(131)I is suggested to have J~π = (31/2~-, 33/2~-) and is primarily attributed to the coupling of an odd proton in the d_(5/2) or g_(7/2) orbit with the (π~2)_0+(νh_(11/2)~(-3)d _(3/2)~(-1))_(15)- configuration in ~(130)Te, responsible for the 15~- isomer in that nucleus. The observed level properties are compared with predictions of a shell-model calculation.