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Article
Report number	arXiv:2401.14018
Title	Long-sought isomer turns out to be the ground state of $^{76}$Cu
Related title	Long-sought isomer turns out to be the ground state of 76Cu
Author(s)	Canete, L. (Jyvaskyla U. ; Surrey U.) ; Giraud, S. (GANIL ; Michigan State U., East Lansing (main)) ; Kankainen, A. (Jyvaskyla U.) ; Bastin, B. (GANIL) ; Nowacki, F. (Strasbourg, IPHC) ; Ascher, P. (LP2I, Bordeaux) ; Eronen, T. (Jyvaskyla U.) ; Alcindor, V. Girard (GANIL ; IJCLab, Orsay) ; Jokinen, A. (Jyvaskyla U.) ; Khanam, A. (Jyvaskyla U. ; Surrey U. ; Helsinki U.) ; Moore, I.D. (Jyvaskyla U.) ; Nesterenko, D. (Jyvaskyla U.) ; De Oliveira, F. (GANIL) ; Penttilä, H. (Jyvaskyla U.) ; Petrone, C. (Bucharest, IFIN-HH) ; Pohjalainen, I. (Jyvaskyla U.) ; De Roubin, A. (Jyvaskyla U.) ; Rubchenyaa, V. (Jyvaskyla U.) ; Vilen, M. (Jyvaskyla U. ; CERN) ; Äystö, J. (Jyvaskyla U.)
Publication	2024-04-22
Imprint	2024-01-25
Number of pages	6
In:	Phys. Lett. B 853 (2024) 138663
DOI	10.1016/j.physletb.2024.138663 (publication)
Subject category	nucl-ex ; Nuclear Physics - Experiment
Abstract	Isomers close to the doubly magic nucleus $^{78}$Ni ($Z=28$, $N=50$) provide essential information on the shell evolution and shape coexistence far from stability. The existence of a long-lived isomeric state in $^{76}$Cu has been debated for a long time. We have performed high-precision mass measurements of $^{76}$Cu with the JYFLTRAP double Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line facility and confirm the existence of such a isomeric state with an excitation energy $E_x=64.8(25)$ keV. Based on the ratio of detected ground- and isomeric-state ions as a function of time, we show that the isomer is the shorter-living state previously considered as the ground state of $^{76}$Cu. The result can potentially change the conclusions made in previous works related to the spin-parity and charge radius of the $^{76}$Cu ground state. Additionally, the new $^{76}$Cu$(n,\gamma)$ reaction $Q$-value has an impact on the astrophysical rapid neutron-capture process.
Copyright/License	preprint: (License: arXiv nonexclusive-distrib 1.0) publication: © 2024 The Author(s) (License: CC BY 4.0)

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