Single-particle and collective excitations in the N=28 isotones Fe 54 and Mn 53

Abstract

The fusion-evaporation reaction S32+Si28 at 125 MeV beam energy was used to populate high-spin states in the semimagic N=28 nuclei Mn53 and Fe54. With a combination of the Gammasphere spectrometer and ancillary devices including the Microball CsI(Tl) array, extensive high-spin level schemes are derived. They exhibit rotational-like collective structures and competing single-particle excitations. The experimental results are compared with predictions from shell-model calculations, for which the inclusion of isopin-symmetry-breaking terms is found to improve the description. An interpretation of the high-spin states is put forward using cranked Nilsson-Strutinsky calculations, indicative of contributions from collective excitations beyond some 8-MeV excitation energy and highlighting the importance of the g9/2 intruder orbital in this energy range.

Metadata

Item Type:

Article

Authors/Creators:

Rudolph, D.
Ragnarsson, I.
Andreoiu, C.
Bentley, M. A. https://orcid.org/0000-0001-8401-3455
Carpenter, M. P.
Charity, R. J.
Clark, R. M.
Ekman, J.
Fahlander, C.
Fallon, P.
Reviol, W.
Sarantites, D. G.
Seweryniak, D.

Funding Information: We would like to thank the accelerator crews and the Gammasphere support staff at Argonne and Berkeley for their supreme efforts. This research used resources of ANL's ATLAS facility, which is a DOE Office of Science User Facility. This work is supported in part by the Swedish Research Council (Vetenskapsrådet, VR 2016-3969) and the U.S. Department of Energy under Grants No. DE-AC02-05CH11231 (LBNL), No. DE-AC02-06CH11357 (ANL), and No. DE-FG05-88ER-40406 (WU). Publisher Copyright: © 2020 authors. Published by the American Physical Society.

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