Si, S, Ca, Ni同位素中的新幻数

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.