High spin states of Pm-141

摘要

The high spin states in the N = 80 odd-A (141) Pm nucleus have been investigated by in-beam gamma-spectroscopic techniques following the reaction Cs-133(C-12, 4n)Pm-141 at E = 65 MeV using a modest gamma detector array, consisting of seven Compton-suppressed high purity germanium detectors and a multiplicity ball of 14 bismuth germanate elements. Thirty new gamma rays have been assigned to Pm-141 on the basis of gamma-ray singles and gammagamma-coincidence data. The level scheme of Pm-141 has been extended upto an excitation energy of 5.2 MeV and spin 35/2 (h) over bar and 16 new levels have been T proposed. Spin-parity assignments for most of the newly proposed levels have been made on the basis of the deduced directional correlation orientation ratios for strong transitions. The meanlives of a few excited states have been determined from the pulsed beam-gammagamma coincidence data using the generalised centroid-shift method. The level structure is discussed in the light of known systematics of neighbouring N = 80 isotonic nuclei. (C) 2003 Elsevier B.V. All rights reserved. [References: 25]