基于核衰变实验数据提取不稳定原子核半径

The nuclear radius is the important property of atomic nuclei, i.e., a complicated quantum many-body system. Up to now, the experimental methods on probing nuclear radii are effective for the nuclides near the stable line. Nevertheless, it is very difficult to take superheavy nuclei and exotic nuclei far away from the stable line as target nuclei due to their short half-lives and the few events of superheavy nuclei, resulting in that the available experimental methods cannot be applied to these unstable nuclei. Hence it is of great importance to theoretically obtain the nuclear charge radii of superheavy nuclei and exotic nuclei far away from the stable line. In this program, we will further develop the cluster model of nuclear decay, consider the isospin effect, the influence from the cluster deformation and the difference between the proton and neutron density distributions in nuclei, and eventually deduce the nuclear charge radii of unstable nuclei from the available experimental decay data. Considering that alpha decay is one of the main decay modes for superheavy nuclei, we obtain the nuclear charge radii of superheavy nuclei from the experimental alpha decay data; we also deduce the nuclear radii of very proton-rich nuclei and neutron-rich light nuclei from the experimental data of proton and cluster emissions. Meanwhile, by combining the relationship between the nuclear radius and the nuclear deformation, the deformation parameters of these target nuclei are supposed to be self-consistently obtained. Moreover, the studied objects are extended to more isomers as well, these results will be useful for future experiments.

原子核半径是原子核这一复杂量子多体系统的重要特性。目前研究核半径的实验方法对于稳定线附近的核素十分有效。而对于超重核以及远离稳定线的奇特核，由于它们寿命很短而且超重核实验事件稀少使得难以将它们制靶，已有的实验方法都还难以应用于这些不稳定原子核。因此，理论上获得超重核和远离稳定线奇特核的电荷半径显得尤为重要。本课题中，我们将进一步发展核衰变的结团模型，考虑同位旋效应、结团形变和核内质子中子密度分布的差异这些因素，从核衰变实验数据提取不稳定核的电荷半径。鉴于alpha衰变是超重核的主要衰变模式之一，我们从alpha衰变实验数据获得超重核和一些不稳定核的电荷半径；还会基于质子放射性及结团放射性的实验数据，提取一些极端丰质子核素和丰中子轻核的半径。同时，结合核半径同核形变之间的关系，拟自洽得到这些目标核的四级形变参数。另外，我们会将研究对象推广到更多的同质异能素，这些结果可以为以后的实验提供帮助。

超重核和滴线附近的缺中子核性质近来备受关注，然而由于其寿命较短以及反应截面一般较小，实验上对这些不稳定核的认识往往比较有限。考虑到核衰变数据是这些不稳定核重要的实验信息，本研究基于核衰变的结团模型，系统研究了这些不稳定核的衰变性质，从衰变实验数据提取了电荷半径和有意义的核结构信息，具有重要的理论意义。主要研究内容如下：1）我们通过考虑核中质子中子密度分布的差异发展了核衰变的结团模型，构建了合理的α粒子和子核间的有效作用势，同时得到了母核的α衰变寿命和衰变能，从而预言了“超重岛”的可能位置。2）通过系统分析同位素和同中子链α衰变预形成因子的变化趋势，我们将其和结构参量如对能，壳修正联系起来，对α结团预形成因子的物理图像给出了比较合理的描述。3) 基于改进的密度依赖的结团模型，我们从重核超重核的α衰变实验数据成功提取了其电荷半径，为得到超重核半径提供了一个可能的新途径。4）在辛弱数框架下解析推导了单j壳的可解态，为接下来进一步研究对关联在α结团化中的作用打下了较好的基础。