American Physical Society, Physical Review C, 6(91), 2015
DOI: 10.1103/physrevc.91.064317
Full text: Unavailable
The β decay of 82 Ge was re-investigated using the newly commissioned tape station BEDO at the electron-driven ISOL facility ALTO operated by the Institut de Physique Nucléaire , Orsay. The original motivation of this work was focused on the sudden occurrence in the light N = 49 odd-odd isotonic chain of a large number of J ≤ 1 states (positive or negative parity) in 80 Ga by providing a reliable intermediate example viz. 82 As. The extension of the 82 As level scheme towards higher energies from the present work has revealed three potential 1 + states above the already known one at 1092 keV. In addition our data allow ruling out the hypothesis that the 843 keV level could be a 1 + state. A detailed analysis of the level scheme using both an empirical core-particle coupling model and a fully microscopic treatment within a Skyrme-QRPA approach using the finite-rank separable approximation was performed. From this analysis two conclusions can be drawn : i-the presence of a large number low lying low spin negative parity states is due to intruder states stemming from above the N = 50 shell closure and ii-the sudden increase, from 82 As to 80 Ga, of the number of low-lying 1 + states and the corresponding Gamow-Teller fragmentation are naturally reproduced by the inclusion of tensor correlations and couplings to 2p-2h excitations.