Speaker
Description
The neutron-rich Z = 32 Ge nuclei are an abundant source of challenges for nuclear structure physics, ranging from demonstrated triaxiality in Ge-76,78. [1,2] through debatable particle-hole structure and strong prolate deformation in Ge-80 [3,4,5] to the N = 50 closed-shell Ge-82. The structure of Ge-81, with a single hole in the N = 50 closed shell, is also remarkable, inasmuch as only a single level (2+) is known in Ge-82 below 2 MeV contrasted with ~15 levels below 2 MeV in Ge-81, including several neutron particle-hole intruder states. For Ge-79, is the dominant structure 3 neutron holes in Ge-82, or are there influences from triaxial Ge-78? Extensive low-spin level structure is established in both nuclei from direct beta and beta-delayed neutron decay of the respective Z = 31 Ga isotopes. New data for higher spin structures will be presented for Ge-79,80,81obtained using Gammasphere at Argonne National Laboratory to study gamma radiation following multi-nucleon transfer [MNT] reactions. Included in the new data is a wide split between the core-coupled 13/2+ and 11/2+ levels that can be theoretically tied to the quadrupole moment of the core 2+ level. [6] Spin and parity of 10+ is proposed for a new level at 4951 keV in Ge-80. These structures will be compared with those of isotonic Zn and Se nuclei along with shell-model calculations.
[1] A. M. Forney et al., PRL 120, 212501 (2018).
[2] A. D. Ayangeakaa et al., PRL 123, 102501 (2019).
[3] A. Gottardo et al., PRL 116, 182501 (2016).
[4] F. H. Garcia et al., PRL 125, 172501 (2020);
S. Sekal, PRC 104, 024317 (2021).
[5] D. Rhodes et al., PRC 105, 024325 (2022);
A. Ait Ben Mennana, PRC 105, 034347 (2022).
[6] V. Paar, Nucl. Phys. A351, 1 (1981);
L. P. Ekström et al., J. Phys. G 7, 85 (1981).
This work was supported in part by the US Department of Energy, Office of Nuclear Physics, under Grant No. DE-FG02-94ER40834 and Contract No. DE-AC02-06CH11357, and used resources of ANLs ATLAS facility, which is a DOE Office of Science User Facility. Involvement of the following people has been invaluable: C. J. Chiara, A. M. Forney, A. D. Ayangeakaa, N. Hoteling, R.V.F. Janssens, I. Stefanescu, M. P. Carpenter, A. A. Hecht, D. Seweryniak, J. Sethi, J. Harker, L. M. Fraile, S. Sekal, J. Greene, M. Alcorta, G. Gürdal, C. R. Hoffman, B. P. Kay, F. G. Kondev, T. Lauritsen, C. J. Lister, E. A. McCutchan, A. M. Rogers, B. Fornal, W. Królas, J. Wrzesiński, T. Pawłat, and R. Broda. Particular appreciation is accorded the late Shaofei Zhu for his many contributions to this and other Gammasphere undertakings.
