Multiparticle-hole states of high spin in N < 50, A ≈ 90 nuclei: 1. The transitional nucleus 4389Tc46

Abstract

High spin states in the nucleus 89 Tc have been studied via the fusion evaporation reaction 58 Ni( 40 Ca,2αp) 89 Tc at 180 MeV beam energy. The NORDBALL γ-ray spectrometer equipped with auxiliary detectors for light particle selection was used to measure γγ- and particle-γγ coin-cidences. Some 60 transitions were placed into a level scheme comprising 38 levels reaching up to 9.2 MeV excitation energy and a possible spin of I = 45/2 h ̷ . The level scheme is compared to those of neighbouring nuclei and interpreted in terms of the spherical shell model. The calculations were performed with different sets of parameters within a restricted π(p 1 2 ) , π(g 9 2 ) , ν(p 1 2 ) and ν(g 9 2 ) configuration space. States above 2.3 MeV excitation energy are well reproduced by shell model calculations based on an empirical residual interaction, whereas collective excitations are suggested to contribute to the wave functions of lower lying states.