N=Z原子核低激发态的质子—中子配对关联

核子配对关联在原子核物理中很重要，以往的研究主要关注于质子—质子配对和中子—中子配对，虽然长期以来人们认为质子—中子配对在N=Z原子核低激发态中可能占据重要地位，然而目前没有明确证据表明质子—中子配对在波函数中是主导成分。近年来借助于新一代放射性束流装置，人们可以测量质量数100左右质子滴线附近N=Z原子核的性质，这为研究质子—中子配对提供了理想平台，质子—中子配对关联是当今国际上原子核物理研究的热点问题之一。本项目计划用原子核壳模型和同位旋守恒的配对近似理论研究N=Z原子核低激发态的质子—中子配对，重点研究以下三个问题：(1)sd壳原子核结合能奇偶性的微观机制，主要讨论质子—中子相互作用奇偶性和Wigner效应的起源；(2)Cd-96原子核负宇称态和非晕转态，考察T=1配对近似和T=0质子—中子配对近似的有效性；(3)N=Z奇奇核低激发态，研究三质子—三中子系统T=0低激发态的物理图像。

Nucleon-pair correlations are very important in nuclear physics. Many efforts have been devoted to understanding proton-proton and neutron-neutron pair correlations. Proton-neutron pair correlation was suggested to play a key role in low-lying states of N=Z nuclei. However, there is no conclusive evidence for dominance of proton-neutron pairs in nuclear wave functions. In recent years, with new-generation facilities of radioactive beams, the study of N=Z nuclei with mass number around 100 near the proton drip line is realizable in laboratories, which provides a great opportunity for studying proton-neutron pairs. Nowadays proton-neutron pair correlation attracts much attention of nuclear physicists in the world. In this project we study proton-neutron pair correlation in the frameworks of the nuclear shell model and the nucleon-pair approximation with isospin symmetry, with our focus on three aspects: (1) the microscopic mechanism of odd-even staggering in binding energies for nuclei in the sd shell, with focus on the origins of odd-even staggering in proton-neutron interactions and Wigner effect; (2) negative-parity states and non-yrast states of Cd-96, for which we shall analyze the validity of T=1 pair approximation and T=0 proton-neutron pair approximation; (3) low-lying states of N=Z odd-odd nuclei, with focus on the pair approximation in T=0 low-lying states of triple-proton-triple-neutron systems.