Existence of a New Isomer of T1/2=24.4 hr in 156Tb

A new transition of 49.630±0.010 keV decaying with a half-life of 24.4±1.0 hr was found in 156 Tb. The isotope assignment was made by the energies of L- and M-subshell internal conversions and the mass assignment by yield ratios of various Tb isotopes at different bombarding energies. The multipolarity of the transition is determined to be E1 from the L-subshell ratios. The decay scheme concerning this new transition is unknown yet.