Lifetime of the yrastIπ=5−state andE1hindrance in the transitional nucleusCe58136

The half-lives o fthe I=5- and 7- yrast stateys with Ex=1978 kev and Ex=2307 keV in the N=78 isotone 136Ce have been measured to be 496(23) ps and 270(24) ps respectively , using the concident fast-timing spectroscopy technique following population by a 124Sn(16O,4n) fusion-evporation reaction at an incident beam energy of 68 MeV.