In-beam gamma -ray spectroscopy of excited states in 141Pm.

Abstract

The level structure of the N = 80 nucleus /sup 141/Pm has been studied in-beam by the /sup 142/Nd(p,2n..gamma..)/sup 141/Pm reaction using a 25-MeV p beam and by the /sup 141/Pr(..cap alpha..,4n..gamma..)/sup 141/Pm reaction using a 47-MeV ..cap alpha.. beam. ..gamma..-ray singles, ..gamma..-..gamma.. coincidence (both prompt and delayed), and angular distribution experiments were performed. We found 42 ..gamma.. rays deexciting 28 states in /sup 141/Pm from the (p,2n..gamma..) reaction and 34 ..gamma.. rays deexciting 22 (generally higher-spin) states from the (..cap alpha..,4n..gamma..) reaction, for a total of 35 known states in /sup 141/Pm. These in-beam experiments, taken together with the results from /sup 141/Sm/sup m/+g decay, yield J/sup ..pi../ assignments for most of the states and have allowed us to deduce the configurations for many of the states. The structures are discussed in terms of single-quasiparticle shell-model and triaxial weak-coupled collective states and are compared with systematics for this nuclear region.