Coulomb excitation of the $\left|T_z\right|=\frac{1}{2}$, $A=23$ mirror pair

• Main Authors: Henderson, J, Hackman, G, Ruotsalainen, P, Holt, J. D, Stroberg, S. R, Andreoiu, C, Ball, G. C, Bernier, N, Bowry, M, Caballero-Folch, R, Cruz, S, Varela, A. Diaz, Evitts, L. J, Frederick, R, Garnsworthy, A. B, Holl, M, Lassen, J, Measures, J, Olaizola, B, O'Sullivan, E, Paetkau, O, Park, J, Smallcombe, J, Svensson, C. E, Whitmore, K, Wu, C. Y
• Format: Journal Article
• Language: English
• Published: 07-05-2020
• Subjects: Physics - Nuclear Experiment; Physics - Nuclear Theory
• DOI: 10.48550/arxiv.2005.03796

Physical Review C 105 034332 (2022) Background: Electric-quadrupole ($E2$) strengths relate to the underlying
quadrupole deformation of a nucleus and present a challenge for many nuclear
theories. Mirror nuclei in the vicinity of the line of $N=Z$ represent a
convenient laboratory for testing deficiencies in such models, making use of
the isospin-symmetry of the systems. Purpose: Uncertainties associated with
literature $E2$ strengths in \textsuperscript{23}Mg are some of the largest in
$T_z=\left|\frac{1}{2}\right|$ nuclei in the $sd$-shell. The purpose of the
present work is to improve the precision with which these values are known, to
enable better comparison with theoretical models. Methods: Coulomb-excitation
measurements of $^{23}$Mg and $^{23}$Na were performed at the TRIUMF-ISAC
facility using the TIGRESS spectrometer. They were used to determine the $E2$
matrix elements of mixed $E2$/$M1$ transitions. Results: Reduced $E2$
transition strengths, $B(E2)$, were extracted for \textsuperscript{23}Mg and
\textsuperscript{23}Na. Their precision was improved by factors of
approximately six for both isotopes, while agreeing within uncertainties with
previous measurements. Conclusions: A comparison was made with both shell-model
and {\it ab initio} valence-space in-medium similarity renormalization group
calculations. Valence-space in-medium similarity-renormalization-group
calculations were found to underpredict the absolute $E2$ strength - in
agreement with previous studies.