摘要
原子核是由强相互作用将核子(包括质子和中子)束缚而成的一个有限量子多体系统,是物质结构的一个重要微观层次,其尺度在费米量级.实验上,在不同能区开展的核反应是研究原子核结构和性质的重要手段.近年来,核反应研究的一个新的增长点是对奇特原子核开展电荷改变反应截面(charge-changing cross section,CCCS)的系统测量,探索可能存在的奇特结构和新奇现象.原子核电荷改变反应截面指的是炮弹原子核在与反应靶中原子核碰撞发生相互作用后,弹核中质子数减少的总概率,反映了参与反应的弹核和靶核之间的碰撞几何截面,可用于提取弹核的电荷半径.本文回顾了世界范围内原子核电荷改变反应截面测量的进展,内容从20世纪80年代末期放射性核束物理开始时的早期工作到远离稳定线丰中子原子核的最新进展;介绍了基于兰州重离子加速器装置(Heavy Ion Research Facility in Lanzhou,HIRFL)开展的研究工作,初步测量了30余个轻原子核的电荷改变反应截面,下一步计划开展sd壳原子核的系统测量,研究Z(N)=14、16处的壳层结构;讨论并分析了当前实验研究中的主要问题和拓展方向,即电荷改变反应截面与相互作用截面的同时测量以及在氢(H)靶上的截面测量,并对基于下一代大科学装置——强流重离子加速器(High-Intensity heavy-ion Accelerator Facility,HIAF)可能开展的工作进行了展望.
The atomic nucleus is a finite open quantum many-body system that is composed of two basic building blocks,proton and neutron.Like many systems governed by the laws of quantum mechanics,a nucleus is an object full of mysteries.Nuclear properties and structure are much more difficult to characterize than those of macroscopic objects and it is almost impossible to build an exact replica of this Fermi-scale nuclear system.In reality,physicists have developed an approach to reveal nature by collisions of two atomic nuclei,i.e.,nuclear reactions,since the very beginning of nuclear physics.One famous example is the Rutherford scattering experiment performed at around 1910,in which the nuclide as a core of atom was discovered.Since the late 1980s,precision measurements of reaction cross section or interaction cross sections played a crucial role in nuclear size determination.This was entwined with the realization of radioactive ion beams(RIB).Such measurements contributed to discovering,for example,the neutron skin and neutron halo,when moving far away from the stability line.The new phenomena and properties found along the experimental advance are meanwhile among the strongest motivations for initiating,constructing,and operating the new generations of nuclear physics facilities worldwide.HIAF,the High-Intensity heavy-ion Accelerator Facility,is now under construction in Huizhou,China.In the last few years,systematic measurements of charge-changing cross sections(CCCS)of exotic nuclei have attracted much attention.It offers a complementary way to study exotic structures that could exist in exotic nuclei.By definition,CCCS refers to the total probability of removing at least one proton from the projectile nuclide.It reflects the geometric overlapping area during the collision.In particular,by combining with the Glauber-type model calculations,precise CCCS data have been used as an effective probe to investigate the proton density distribution of unstable atomic nuclei.This method is suitable for the investigation of exo
作者
孙保华
Baohua Sun(School of Physics,Beihang University,Beijing 102206,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2020年第34期3886-3897,共12页
Chinese Science Bulletin
基金
国家重点研发计划(2016YFA0400504)
国家自然科学基金(U1832211,11922501,11961141004)资助。
关键词
原子核
壳模型
放射性核束
电荷改变反应截面
固态氢靶
atomic nuclei
shell model
radioactive ion beam
charge-changing cross section
solid hydrogen target
