Speaker
Description
In a Letter, Brown described the effects on paring and collectivity associated with p1/2 orbitals. [1]. The consequence is to create a collectivity gap at N = 32 as noted for Ca-53. A similar effect was noted for N = 40 where the p-1/2 orbital plays a strong role in the evolution of the observed structure in Zn-69,70,71. In this region, the p-1/2 orbital inhibits collectivity near N = 40 and serves as a reservoir for neutrons. The structure for Zn-69 has been reported in detail from a number of sources, including the capture gamma spectrum from the EXIL facility by Bączyk at al. [2]. For 71Zn, however, many fewer data are available. Bottoni et al reported high-spin positive-parity structures that included calculations for Zn-71 that did not provide a good fit to the observed levels and suggested oblate shapes. The remarkably low paring gap for Zn-70, as well as occupancies for Ni and Zn nuclei, were also discussed. In this presentation, new data from the capture-gamma study of the Zn-70(n,gamma) Zn-71 reaction will be reported using data collected at the NG7 cold neutron prompt gamma ray activation analysis (CNPGAA) instrument at the NIST Center for Neutron Research (NCNR) Reactor at the National Institute of Standards and Technology. [4] These results showing population of low-spin levels will be incorporated into data from both decay and reaction sources to provide a much more detailed low- and medium-energy structure for Zn-71. [5] The inhibited collectivity around N = 40 will be discussed, along with the (g9/2)+3 cluster structure available by dipping into the neutron reservoir to achieve 3 neutrons beyond Zn-68.
[1]. B. A. Brown, Physical Review Letters 111, 162502 (2013)
[2]. P. Bączyk at al., EPJ Web of Conferences 93, 01042 (2015).
[3]. S. Bottoni et al. Physics Letters B 775, 271 (2017)
[4]. A. L. Hutchison, J. A. Harker, W. B. Walters, M. Waite, R. Paul, Bull. Am. Phys. Soc., 60 # 4, J3.3 (2015).
[5]. I. Celikovic et al., Physical Review C 91, 044311 (2015).
| Contribution category | Experiment |
|---|---|
| Presenter status | Faculty/Staff |