Decay properties of long-lived isomers in the odd-odd N=81 nucleus Tb146 compared to the Ho148 and Tm150 nuclei

Excited states of the Tb-146 nucleus have been studied using gamma-ray and electron spectroscopy in off-beam and in-beam modes following Sn-112(Ar-40, 3n3p) reaction with the use of the OSIRIS-II, HPGe detector array and the conversion electron spectrometer. The multipolarity of the 343 keV transition deexciting the (7(-)) level in Tb-146 shows mainly an E2 nature and the first excited state above the 23 s isomer is assigned as a (5(-), 6(-)) state. The log f t values have been deduced for 11 beta(+)/EC transitions populating excited states in (14)6Gd. The systematic behavior of spins and parities of the long-lived levels at 0 + x keV and the first excited states above them in the N = 81 isotones Tb-146, Ho-148, and Tm-150 is discussed.