基于Weizsaecker-Skyrme(WS)原子核质量公式,系统研究了Si,S,Ca,Ni同位素链的壳能隙、原子核形变以及电荷均方根半径.WS质量公式的计算结果能够非常好地再现已有的实验数据,对于885个已测原子核电荷半径的rms偏差仅为0.022 fm;对于2353个已测原子核质量的rms偏差仅为298 ke V.除了已知的中子幻数,WS公式还预言N=14,16以及32也可能是幻数.对于中等质量以及重核,基于核质量得到的经验壳能隙能够比较敏锐地给出幻数信息.原子核电荷半径也能给出幻数信息,不过需要大幅度提高电荷半径测量精度并开展丰中子核电荷半径的系统测量.
The shell gaps, nuclear deformations, and rms charge radii of Si, S, Ca, and Ni isotopes were systematically investigated with the Weizsaecker-Skyrme (WS) mass formula. The measured data were reproduced remarkably well by the WS calculations. The rms deviation was only 298 keV with respect to the 2353 measured masses and only 0.022 fm with respect to the 885 measured charge radii. In addition to the known neutron magic numbers, the WS formula predicts that the neutron numbers N=14, 16, and 32 could also be magic numbers. The empirical shell gaps based on the nuclear masses of intermediate and heavy nuclei are sensitive observables which can be used to study the shell closures. To obtain helpful shell closure information from the nuclear rms charge radii, the precisions of the experimental measurements for neutron-rich nuclei should be improved further and more data are still required.