Sub-nanosecond Half-life Measurement of the Yrast Iπ=5− State in the N=78 Nucleus Ce58136 using Fast-timing Coincident Gamma-ray Spectroscopy

We report on the measurement of the half-life of the yrast I π = 5 − state in the transitional nucleus 136 Ce using a combined HPGe-LaBr3(Ce) scintillator gamma-ray detection array. The measured value for the E 1 decay is approximately half a nanosecond, which corresponds to an E 1 decay strength of approximately 2 × 10 − 6 Wu. This value is in line with single-particle type E 1 decays in this mass region and suggests no sign of additional K-hindrance associated with axially symmetric quadrupole deformations observed for lighter cerium isotopes.