$l$-forbidden $\mathbf{M1}$ strengths near $^{100}$Sn from knockout reactions in Cd and Sn

T. J. Gray; K. L. Jones; R. Grzywacz; B. A. Brown; A. Gade; B. C. He; T. Miyagi; A. Peter; M. J. Basson; T. Beck; C. M. Campbell; G. Cerizza; J. Chung-Jung; I. Cox; P. Farris; R. Ghimire; S. Gillespie; M. Grinder; A. Hill; S. D. Pain; A. Palmisano-Kyle; K. P. Rykaczewski; D. Weisshaar; M. Williams

arXiv · 2607.02184

$l$-forbidden $\mathbf{M1}$ strengths near $^{100}$Sn from knockout reactions in Cd and Sn

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Abstract

Neutron knockout reactions on beams of $^{104,102}$Cd, and $^{104}$Sn are presented. States in the residual $^{103,101}$Cd and $^{103}$Sn nuclei are populated, including low-lying $7/2^+$ states of $\nu g_{7/2}$ character. These states have half-lives $\approx 400$ ps due to their low energy and hindered $B(M1; 7/2^+ \rightarrow 5/2^+)$ strengths. The excited-state half-lives were measured using their Doppler-shifted lineshapes, and the resulting $B(M1)$ strengths are compared to Valence Space In Medium Similarity Renormalization Group (VS-IMSRG) calculations. The VS-IMSRG calculations under-predict the $l$-forbidden $M1$ strengths in the $^{100}$Sn region, as well as in other regions of the nuclear chart near $^{40}$Ca and $^{208}$Pb.

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T. J. Gray, K. L. Jones, R. Grzywacz, B. A. Brown, A. Gade, B. C. He, T. Miyagi, A. Peter, M. J. Basson, T. Beck, C. M. Campbell, G. Cerizza, J. Chung-Jung, I. Cox, P. Farris, R. Ghimire, S. Gillespie, M. Grinder, A. Hill, S. D. Pain, A. Palmisano-Kyle, K. P. Rykaczewski, D. Weisshaar, M. Williams. 2026-07-02. $l$-forbidden $\mathbf{M1}$ strengths near $^{100}$Sn from knockout reactions in Cd and Sn. https://arxiv.org/abs/2607.02184

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