Shell quenching phenomena in nuclear charge radii are typically observed at the well-established neutron magic numbers. However, the recent discovery of potential new magic numbers at the neutron numbers $N = 32$ and $N = 34$ has sparked renewed interest in this mass region. This work further inspects into the charge radii of nuclei around the $N = 28$ shell closure using the relativistic Hartree-Bogoliubov model. We incorporate meson exchange and point-coupling effective nucleon-nucleon interactions alongside the Bogoliubov transformation for pairing corrections. To accurately capture the odd-even staggering and shell closure effects observed in charge radii, neutron-proton correlations around Fermi surface are explicitly considered. The charge radii of Ca and Ni isotopes are used to test the theoretical model and show an improvement with neutron-proton pairing corrections, in particular for neutron-rich isotopes. Our calculations reveal a inverted parabolic-like trend in the charge radii along the $N = 28$ isotones for proton numbers $Z$ between 20 and 28. Additionally, the shell closure effect of $Z = 28$ persists across the $N = 28$, 30, 32, and 34 isotonic chains, albeit with a gradual weakening trend. Notably, the significantly abrupt changes in charge radii are observed across $Z = 22$ along both the $N = 32$ and $N = 34$ isotonic chains. This kink at $Z = 22$ comes from the sudden decrease of the neuron-proton correlation around Fermi surfaces across $Z = 22$ for $N = 30$, 32, and 34 isotones, and might provide a signature for identifying the emergence of neutron magic numbers $N = 32$ and 34. Furthermore, the calculated charge radii for these isotonic chains ($N = 28$, 30, 32, and 34) can serve as reliable guidelines for future experimental measurements.
Puzzling Radii of Calcium Isotopes: $^{40}{\rm Ca} \rightarrow ^{44}{\rm Ca} \rightarrow ^{48}{\rm Ca} \rightarrow ^{52}{\rm Ca}$, and Duality in the Structure of $^{42}_{14}{\rm Si}_{28}$ and $^{48}_{20}{\rm Ca}_{28}$
New relativistic effective interaction for finite nuclei, infinite nuclear matter and neutron stars
我们利用布巴内斯瓦尔物理研究所新近发展的相对论力对有限核、无限核物质和中子星的性质进行了研究。利用这个力，我们计算了一些原子核的结合能、电荷半径和中子皮厚度。从超重元素Z=120的基态性质可以看出，在中子数N=172、184和198时，壳层隙出现了明显的变化，说明中子数N=172、184和198是很神奇的。纯中子物质状态方程的低密度行为与其他微观模型是相容的。与核对称能一样，它在饱和密度下的斜率和曲率参数与从各种实验数据中提取的参数是一致的。用$\it beta-equilibrium$中核子和轻子组成的状态方程计算了中子星的性质，与Steiner和Nättilä的X射线观测结果符合得很好.我们发现该中子星的最大质量为2.15 $M_{\odot}$，半径为11.936 km。在此参数范围内，质量为1.4 $M_\odot$的{ \it正则}中子星的半径为13.242 km，潮汐形变率为3.910 $\times$ 10 $^{36}$ g cm $^2$ s $^2$.
Precise Determination of Electric Quadrupole Moments and Isotope Shift Constants of Yb$^+$ in Pursuance of Probing Fundamental Physics and Nuclear Radii
