Nuclear decay scheme studies of some tantalum and terbium isotopes

Abstract

A previously unreported isotope of' terbium~ Tb , was produced. Its gamma-ray spectrum was studied and its h~lf life was deter= mined to be 18.5±0.5 hr. The similarity to the half lives of two 151 154 neighboring isotopes, 19-hr Tb and. 17-hr Tb :; e~plains why it was previously overlooked. 161 The decay scheme of Tb was studied and precise transition energies are reported. The lifetimes of two excited states were measured and used to resolve a ~uestion of transition se~uence encountered by previous investigators. Three new isotopes of tantalum were discovered" They are 3.7-hr Ta 1 73, 1.2~hr Ta 1 7 4 , and 11-hr Ta 175 • Tantalum-175 was studied. in detail and a decay scheme is presented using eight of the transitions observed in conversion-ele::ctron studies. Four excited states are proposed, and Nilsson quantum numbers are assigned;, Electron-sensitive nuclear track emulsions were used in conjunction with electron spectrographs, and the usefulness of the method of track counting is discussed..