Isospin symmetry in the $T = 1, A = 62$ triplet

K. Wimmer, P. Ruotsalainen, S. M. Lenzi, A. Poves, T. Hüyük, F. Browne, P. Doornenbal, T. Koiwai, T. Arici, K. Auranen, M. A. Bentley, M. L. Cortés, C. Delafosse, T. Eronen, Z. Ge, T. Grahn, P. T. Greenlees, A. Illana, N. Imai, H. JoukainenR. Julin, A. Jungclaus, H. Jutila, A. Kankainen, N. Kitamura, B. Longfellow, J. Louko, R. Lozeva, M. Luoma, B. Mauss, D. R. Napoli, M. Niikura, J. Ojala, J. Pakarinen, X. Pereira-Lopez, P. Rahkila, F. Recchia, M. Sandzelius, J. Sarén, R. Taniuchi, H. Tann, S. Uthayakumaar, J. Uusitalo, V. Vaquero, R. Wadsworth, G. Zimba, R. Yajzey

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Excited states in the $T_z = 0, -1$ nuclei $^{62}$Ga and $^{62}$Ge were populated in direct reactions of relativistic radioactive ion beams at the RIBF. Coincident \grays were measured with the DALI2$^+$ array and uniquely assigned to the $A=62$ isobars. In addition, $^{62}$Ge was also studied independently at JYFL-ACCLAB using the ${}^{24}$Mg(${}^{40}$Ca,$2n$)${}^{62}$Ge fusion-evaporation reaction. The first excited $T=1, J^\pi =2^+$ states in $^{62}$Ga and $^{62}$Ge were identified at $979(1)$ and $965(1)$~keV, respectively, resolving discrepant interpretations in the literature. States beyond the first $2^+$ state in $^{62}$Ge were also identified for the first time in the present work. The results are compared with shell-model calculations in the $fp$ model space. Mirror and triplet energy differences are analyzed in terms of individual charge-symmetry and charge-independence breaking contributions. The MED results confirm the shrinkage of the $p$-orbits' radii when they are occupied by at least one nucleon on average.
Original languageEnglish
Article number138249
Number of pages7
JournalPhysics Letters B
Early online date6 Nov 2023
Publication statusPublished - 10 Dec 2023

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