Abstract
An experiment has been performed to populate several extremely neutron-deficient nuclei around the mass-140 region of the nuclear chart, using a beam of on a target at an energy of 315 MeV. Analysis of these data using recoil-isomer tagging has established that the yrast , bandhead state in is isomeric with a half-life of 1.5(1) μs. This isomeric state decays via a 43-keV, probable- transition to a ) state. Consideration of the theoretical Nilsson orbitals near the Fermi surface suggests that the state has a configuration, which decays to the state with a configuration. Differences in the shape-driving effects for these two configurations is reasoned to be responsible for the long half-life of the isomeric state. The non-observation of other rays in prompt or delayed coincidence with the 43-keV transition suggests that this transition may feed another, longer lived isomeric state with a half-life of the order of milliseconds or greater. However, the present experiment was not sensitive to the decay of this new ) state by internal conversion or even decay.
- Received 8 May 2007
DOI:https://doi.org/10.1103/PhysRevC.78.034304
©2008 American Physical Society