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

Author:

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. Joukainen, R. 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

Keyword:

Nuclear Experiment, Nuclear Experiment (nucl-ex)

journal:

date:

2023-10-10 16:00:00

Abstract

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.

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