$\left|T_z\right|=\frac{1}{2}$、$A=23$镜对的库仑激发
Coulomb excitation of the $\left|T_z\right|=\frac{1}{2}$, $A=23$ mirror pair
摘要：
工作背景：电四极（$E2$）强度与原子核的四极形变有关，对许多核理论提出了挑战。在$N=Z$谱线附近的镜像原子核代表了一个方便的实验室，利用系统的同位旋对称性来测试这种模型的缺陷。目的：与文献中\textsuperscript{23} Mg中的$E2$强度相关的Understanding是$sd$ -壳中$T_z=\left|\frac{1}{2}\right|$核中最大的。本工作的目的是提高这些值是已知的精度，使更好地与理论模型进行比较。方法：使用TIGRESS光谱仪在TRIUMF-ISAC设施中对$^{23}$ Mg和$^{23}$ Na进行库仑激发测量。它们用于确定混合$E2$ / $M1$跃迁的$E2$矩阵元。结果：提取了\textsuperscript{23} Mg和\textsuperscript{23} Na的还原$E2$转变强度$B(E2)$。两种同位素的精确度都提高了约6倍，同时与以前的测量结果在不确定性范围内保持一致。结论：比较了壳模型和{ \it ab initio}价空间介质相似重整化群计算的结果。价空间中的介质相似重整化群计算被发现低估的绝对$E2$强度-与以前的研究一致。
英文摘要：
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.
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