Level structure of proton-richN=83 Nuclei150Ho and152Tm

Abstract

The yrast levels of the N=83 odd-odd nuclei ~S~ and 152Tm have been studied by 7-ray spectroscopy following reactions induced by 240-250 MeV 6~ ions. Isomers have been identified in tS~ at 1.096, 2.625 and ~8.0 MeV and in aSZTm at 2.555 and ~6.3 MeV, and the level schemes of both nuclei have been established up to 2.6 MeV. The level spectra are interpreted using the shell model in terms of the coupling of anfT/2, h9/z or i~3/2 valence neutron to the yrast excitations of the neighboring N= 82 nuclei.

Level structure above the 17+ isomeric state in Tm8369152

“…structure features. For example, differences between the level structures below the 17 + isomeric states in 150 Ho and 152 Tm isotones have been provisionally interpreted to arise from the strong influence of the π 0h 11/2 -ν0h 9/2 interaction; however, that needs confirmation [4].…”

“…The overall aim of such studies is to test models with particular components of the nucleon-nucleon interaction. In an empirical approach, this interaction is extracted from the data or taken from systematics [2,4,5]. For example, experimental knowledge of the structure of 148 65 Tb 83 [6] determines the π 0h 11/2 -ν1f 7/2 interaction or that of 146 63 Eu 83 [7] fixes the (π 0h 11/2 ) −1 -ν1f 7/2 interaction.…”

“…The substantial evidence for a subshell gap at proton number Z = 64 [1] triggered a great deal of work on proton-rich nuclei in the A ≈ 150 mass region [2][3][4][5][6][7]. The similarities between the doubly magic nuclei 146 Gd and 208 Pb [1] and the expected influence of the proton-neutron interaction on structural features as observed in the 100 Sn region [3,[8][9][10]] also fueled further interest.…”

“…A comparison with the calculations using empirical interactions revealed the crucial roles of the nucleon occupation of the π 0h 11/2 orbital. The interaction between protons in the π 0h 11/2 orbital and neutrons in the ν0h 9/2 orbital is also expected to influence the level structures exhibited by nuclei in this region [4]. As protons are added above the Z = 64 subshell closure or neutrons above the N = 82 shell closure, the proton-neutron interaction is expected to strengthen and have an effect on the nuclear * Present address: School of Computing, Engineering and Physical Sciences, University of the West of Scotland, Paisley, PA1 2BE, United Kingdom.…”

“…Consequently, theoretical interpretations of the levels in nuclei with Z ∼ 64 and N ∼ 82 are currently feasible. In particular, if one assumes that only protons in the π 0h 11/2 orbital and neutrons in the ν1f 7/2 orbital are active, then the shell-model calculations can be performed relatively easily and a comparison with data can be used to refine or develop nuclear structure models [2,4,5]. The overall aim of such studies is to test models with particular components of the nucleon-nucleon interaction.…”