Level structures of 56,58Ca cast doubt on a doubly magic 60Ca

Chen, S.; Browne, F.; Doornenbal, P.; Lee, J.; Obertelli, A.; Tsunoda, Y.; ..., ...; Gašparić, Igor; ..., ...; Yan, D.; Yang, Z.; Yasuda, M.; Zanetti, L. (2023) Level structures of 56,58Ca cast doubt on a doubly magic 60Ca. Physics Letters B, 843 . ISSN 03702693

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Abstract

Gamma decays were observed in Ca-56 and Ca-58 following quasi-free one-proton knockout reactions from Sc-57,Sc-59 beams at approximate to 200MeV/nucleon. For Ca-56, a gamma ray transition was measured to be 1456(12) keV, while for Ca-58 an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the 2(1)(+) -> 0(gs)(+) decays, and were compared to results from ab initio and conventional shell-model approaches. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for 2(1)(+) level energies, two-neutron separation energies, and reaction cross sections, corroborating the formation of a new nuclear shell above the N= 34 shell. Its constituents, the 0f(5/2)and 0g(9/2) orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic Ca-60 and potentially drives the dripline of Ca isotopes to Ca-70 or even beyond.

Item Type:	Article
Uncontrolled Keywords:	experimental nuclear physics; radioactive beams; gamma spectroscopy; nuclear shell model
Subjects:	NATURAL SCIENCES NATURAL SCIENCES > Physics NATURAL SCIENCES > Physics > Nuclear Physics
Divisions:	Division of Experimental Physics
Projects:	Project title Project leader Project code Project type Zemljovid atomskih jezgara - neutronski bogata strana-NeRiS-Land Suzana Szilner IP-2018-01-1257 HRZZ Nuklearna struktura i reakcije: eksperimentima prema neutronskoj liniji kapanja-SR-ETNo Suzana Szilner IP-2013-11-7194 HRZZ
Depositing User:	Virna Brumnić
Date Deposited:	05 May 2025 10:25
URI:	http://fulir.irb.hr/id/eprint/9808
DOI:	10.1016/j.physletb.2023.138025

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