Decay schemes from the (n,y) reaction on 151Eu and 181Ta

Abstract

Gamma-rays were detected in both singles and coincidence in order to establish the decay schemes of the nuclei 152Gd, 152Sm and 182W, which arise from the radioactive decay of 152Eu and 182Ta prepared from the (n,gamma) reaction on 151 Eu and 181Ta.Two high resolution Ge(Li) detectors and one intrinsic germanium detector were employed for the measurements of the 7-ray energies and relative intensities, allowing the logft values, multipolarities, spins/parities and transition probabilities to be deduced for the 152Gd, 152Sm and 182W. The fast-slow coincidence technique was used with two Ge(Li) detector and data recorded with a microcomputer for off-line analysis. Consequently, following these measurements, the level schemes of the above nuclei were built up incorporating several new energy levels and transitions. Comparisons are made with the predictions of current nuclear models. In particular, the application of the group theoretical symmetries of the Interacting Boson Model (IBM) are discussed. The calculations were carried out using the program package PHINT for determing the energy levels, in conjunction with FBEM for evaluating the transition rates. The nuclei investigated test the SU(5)→ SU(3) transitional region in the case of 152Gd and 152Sm, and the SU(3) rotational limit for the 182W.