轻质量原子核中子发射的衰变宽度理论描述  

Theoretical description of the decay width of neutron emission in light nuclei

作　　者：蔡博帅 袁岑溪 Boshuai Cai;Cenxi Yuan(Sino-French Institute of Nuclear Engineering and Technology,Sun Yat-sen University,Zhuhai 519082,China)

机构地区：[1]中山大学中法核工程与技术学院,珠海519082

出　　处：《科学通报》2022年第23期2782-2789,共8页Chinese Science Bulletin

基　　金：广东省基础与应用基础研究重大项目(2021B0301030006);国家自然科学基金(11775316)资助。

摘　　要：本文尝试提出描述轻质量原子核中子发射衰变宽度的理论公式.使用Wentzel-Kramers-Brillouin(WKB)近似和R-matrix方法计算了单中子发射的衰变宽度.通过WKB近似和R-matrix方法的隧穿因子,得到描述单中子发射宽度一般规律的三变量公式,使用该公式计算的结果与实验值的均方根误差小于0.6个数量级.研究结果有助于进一步研究中子滴线附近丰中子核的性质.The study of nuclear decay is an important field for investigating nuclear structures and nucleosynthesis.The existence of Coulomb interaction makes the emission of charged particles have a relatively long half-life.Based on the WKB approximation and the R-matrix method,several empirical formulas describing the proton decay,alpha decay,and emission of charged clusters have been proposed,e.g.,the new Geiger-Nutall formula and the Universal Decay Law.The investigation of beta delayed proton(s)decay enhances understanding of isospin symmetry breaking and mixing.Because of the absence of Coulomb interaction,the half-life of neutron emission is much shorter.For neutron-unbound states,the experimentalists concentrate more on discovering neutron-rich nuclei beyond the neutron-drip line.The theorists are more interested in establishing models for a specific nucleus to describe the one-and two-neutron emission phenomenon.The universal law describing the general characteristics of single neutron emission is rarely taken into account.This paper applies the WKB approximation and the R-matrix method to investigate the decay width of the single neutron emission.The square well potential and the harmonic oscillator potential are used as input of nuclear potential.As to the Rmatrix method,the sine function basis and the Lagrange basis are applied,respectively.Both the WKB approximation and the R-matrix method calculate the decay width in two parts:The formation factor and the penetration factor.A threevariable formula is deduced from the penetration factor of these two theories.As to the ground states emitting a single neutron,the root-mean-square of log_(10)Γ_(exp)/Γ_(cal)for the three-variable formula is only 0.31,which shows a good description ability.The decay widths of the other 13 nuclides are thus predicted.For the excited states,the direct application of the two theories presents deviation within an order of about 3.The decay width is found to be sensible to the radius of nuclear force and less sensible to the depth of

关 键 词：单中子发射 衰变宽度 WKB近似 R-matrix方法 唯象公式 

分 类 号：O571.5[理学—粒子物理与原子核物理]