1. Long-sought isomer turns out to be the ground state of $^{76}$Cu
- Author
-
Canete, L., Giraud, S., Kankainen, A., Bastin, B., Nowacki, F., Ascher, P., Eronen, T., Alcindor, V. Girard, Jokinen, A., Khanam, A., Moore, I. D., Nesterenko, D., De Oliveira, F., Penttilä, H., Petrone, C., Pohjalainen, I., De Roubin, A., Rubchenyaa, V., Vilen, M., and Äystö, J.
- Subjects
Nuclear 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., Comment: 8 pages, 4 figures
- Published
- 2024