Nuclear level scheme of 182Ta nucleus via thermal neutron capture reaction and γ − γ coincidence measurement

Abstract

Two-step gamma cascades from the ¹⁸²Ta compound state, produced via thermal neutron capture of ¹⁸¹Ta target, were measured using a γ-γ coincidence spectrometer. A partial nuclear level scheme (NLS), comprising of 67 primary transitions and associated intermediate levels together with 157 secondary transitions, has been constructed from the measured data. Comparison between the currently adopted NLS and that extracted from the Evaluated Nuclear Structure Datafile (ENSDF) library indicates that 32 primary, 52 intermediate levels, and 11 secondary transitions are mostly the same. The remaining 35 primary, 15 intermediate levels, and 146 secondary transitions are thus new data observed in the present work. Additionally, the spin value of the detected levels are found in excellent agreement with those in the ENSDF library. In particular, a unique spin value has been assigned to 25 detected levels whereas the spin value of 15 existing levels has been refined. All the discrepancies between data from this work and those from the ENSDF library have been well explained. Data newly observed in this work should be, therefore, recommended to update the currently adopted NLS of ¹⁸²Ta in the ENSDF library.