原子核第一激发能的统计规律

原子核的第一激发态能级是所有激发态能级中最重要的一条能级，在一定程度上可直接反映该核素的稳定性。通过对2 125个核素的第一激发态能级纲图进行统计分析，发现传统幻数位置的第一激发能明显高于邻近核素的第一激发能，亦对应于同位素链、同中子素链上原子核第一激发能最大的核素。对于第一激发能较大且明显偏离传统幻数位置的少量核素，发现都具有同质异位素相似态或为裂变核的混合能级，这些给出的值是否是第一激发态，在理论和实验上仍存在一定的不确定性；而对于原子核第一激发能最大的核素，其自旋宇称为2+的最多（高达42%）。对于中重核区内的偶偶核，其第一激发能与价核子N_pN_n关系明显趋于指数的衰减形式。

Statistical Features of the First Excitation Energy of Nuclei

The first excited state plays a significant role for all excited states of nuclei besides the ground state. The first excitation energy which can directly reflect the stability of the nuclei to some extent is one of the most important features of the excited states. Through statistical analysis of the first excitation energies of 2 125 nuclei, one can find that the first excitation energies at the traditional magic number positions are significantly higher than those of the adjacent nuclei, as well as the nuclei with the highest first excited energy of both the isotopic and isotonic chains. For a small number of nuclei significantly deviating from the positions of the traditional magic number, it is also found that their high first excitation energies were the Isobaric Analog States (IAS) of the adjacent nuclei or some mixed levels of fissile nuclei. For the highest first excitation energy of the isotopic and isotonic chains, the number of their spins and parities with 2+ of the first excited state is most up to 42%. For even-even nuclei in the range of mass number 100~200, the first excitation energies can be described by the exponential decay function with the valence nucleon N_pN_n.