Gamma rays from excited states feeding a proton-emitting isomeric-state in 151 Lu have been observed for the first time. Comparison with state-of-the-art nonadiabatic quasiparticle calculations indicates an oblately deformed, 3/2 + proton-emitting state with a quadrupole deformation of β 2 = −0.11. The calculations suggest an increase in quadrupole deformation, to β 2 = −0.18, with increasing spin which is understood in terms of the mixing of Nilsson states at the Fermi surface. It is also shown that the proton decay half-life is consistent with that from a 3/2 + state with a quadrupole deformation of β 2 = −0.12.

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An in-beam study has been performed to further investigate the known isomeric decays and to identify T = 1 excited states in the medium-heavy N = Z = 33 nucleus 66 As. The fusion-evaporation reaction 40 Ca( 28 Si,pn) 66 As was employed at beam energies of 75 and 83 MeV. The half-lives and ordering of two known isomeric states in 66 As have been determined with improved accuracy. In addition, several prompt γ -ray transitions from excited states, both bypassing and decaying to the isomeric states in 66 As, have been observed. Most importantly, candidates for the 4 + → 2 + and 6 + → 4 + transitions in the T = 1 band have been identified. The results are compared with shell-model calculations using the modern JUN45 interaction in the pf 5/2 g 9/2 model space.alignment of the valence nucleons [5], shape changes as a function of spin [6], and the evolution of nuclear radii along the yrast line [7].Two isomeric states have been previously identified in 66 As [8]. In more recent studies, the decay of the isomers was used as a tag to identify excited states above the isomeric states [9] and new prompt γ rays were associated with 66 As, without the ability to observe delayed transitions, in Ref.[10]. In the current work, both the isomeric and the prompt T = 0 and T = 1 structures have been studied. The half-lives and ordering of the isomeric states have been determined with improved accuracy and internal conversion coefficients have been deduced for the transitions deexciting the isomers, allowing the determination of the corresponding experimental B(E2) transition strengths. Recent experimental [10] and theoretical [11] work has investigated the CED in the A = 66 ( 66 As/ 66 Ge) and A = 70 ( 70 Br/ 70 Se) systems. The present work agrees with some of the findings reported in Ref.[10], but differs for the T = 1, I π = 6 + state resulting in a positive CED behavior.The odd-odd N = Z nuclei in the mass A ∼ 60-70 region provide an opportunity to test shell-model (SM) interactions and model spaces for these midmass nuclei. In the present work SM calculations have been performed using the modern JUN45 interaction [12] and a pf 5/2 g 9/2 model space. The experimental results are compared with the SM predictions in terms of level energies, CED, and B(E2) values.

Lifetime measurements have been made in the neutron-deficient nucleus 109 Te using the coincident recoil distance Doppler-shift method. The experimental B(E2) values have been compared with state-of-the-art shellmodel calculations using the monopole-corrected realistic charge-dependent Bonn nucleon-nucleon potential. Lifetimes in the νh 11/2 band are consistent with an interpretation based on the deformation driving properties of a single valence neutron outside of the even-even tellurium core and highlight the unexpected presence of collective behavior as the N = 50 shell closure is approached. Lifetime measurements for the low-lying positive-parity states also appear to correlate well with shell-model calculations. In addition, a comparison with the proton-unbound nucleus 109 I suggests that the presence of a single decoupled valence proton affects the total measured B(E2) strengths in a manner that is not currently well understood.

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