Identification of the slow E3 transition C-136(s)m -> Cs-136 with conversion electrons
ABSTRACT We performed at ISOLDE the spectroscopy of the decay of the 8(-) isomer in Cs-136 by. and conversion-electron detection. For the first time the excitation energy of the isomer and the multipolarity of its decay have been measured. The half-life of the isomeric state was remeasured to T-1/2 = 17.5(2) s. This isomer decays via a very slow 518-keV E3 transition to the ground state. In addition to this, a much weaker decay branch via a 413-keV M4 and a subsequent 105-keV E2 transition has been found. Thus we have found a new level at 105 keV with spin 4(+) between the isomeric and the ground state. The results are discussed in comparison to shell-model calculations.