^(293,294)119与^(294,295)120超重核衰变性质理论预言  

Predictions of the decay properties of the superheavy nuclei^(293,294)119 and^(294,295)120

作　　者：王震[1] 任中洲 WANG Zhen;REN Zhongzhou(School of Physics Science and Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Advanced Micro-Structure Materials(MOE),Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学物理科学与工程学院,上海200092 [2]同济大学先进微结构材料教育部重点实验室,上海200092

出　　处：《核技术》2023年第8期107-113,共7页Nuclear Techniques

基　　金：国家自然科学基金(No.12035011,No.12022517,No.11975167,No.11947211,No.11905103,No.11881240623,No.11961141003);国家重点研发计划(No.2018YFA0404403);中央高校基本科研业务费专项(No.22120200101);澳门科学技术发展基金(No.0048/2020Al)资助。

摘　　要：熔合蒸发反应^(243)Am(^(54)Cr,xn)^(297−x)119以及^(243)Am(^(55)Mn,xn)^(298−x)120是最近核物理学家提出的合成Z为119及120新元素的可能途径,α衰变是实验上鉴定新元素或新核素合成的有力工具。利用改进的密度依赖结团模型(Improved Density-dependent Cluster Model,DDCM+),对于熔合蒸发反应^(243)Am(^(54)Cr,xn)^(297−x)119以及^(243)Am(^(55)Mn,xn)^(298−x)120蒸发3或4个中子得到的反应产物^(293,294)119与294,295120的α衰变半衰期进行了理论预言。在此基础上,进一步分析了^(293,294)119与^(294,295)120核素α衰变过程与自发裂变以及β衰变等不同衰变模式之间的竞争关系。通过研究发现,对于绝大多数核,α衰变模式占主导地位,但沿着α衰变链,随着质量数减少至A=261附近,自发裂变以及β衰变半衰期与α衰变半衰期逐渐相近。相关理论结果对于未来Z为119及120新元素的合成工作具有一定的参考意义。[Background]To date,various nuclides up to Z=118 have been discovered and synthesized,raising the challenge of synthesizing nuclides with Z≥119.Recently,the fusion-evaporation reactions 243Am(^(54)Cr,xn)^(297−x)119 and 243Am(^(55)Mn,xn)^(298−x)120 have been suggested as methods for synthesizing new elements with Z=119 and 120.Asα-decay is a powerful tool for the identification of new elements or nuclides,accurate predictions of theα-decay properties of the reaction products could be a useful reference for future experiments.[Purpose]This study aims to provide quantitative predictions of theα-decay,spontaneous fission,andβ-decay half-lives for theα-decay chains of^(293,294)119 and^(294,295)120 and to demonstrate the competition between the decay modes for these nuclei.[Methods]An improved density-dependent cluster model(DDCM+)is used to calculate theα-decay half-lives,taking the anisotropy of the surface diffuseness into account.The spontaneous fission half-lives are calculated using the Karpov formula,which is related to the fissility parameter and fission barrier height of the potential energy surface.Theβ-decay half-lives are determined using a finite-range droplet model(FRDM).[Results]The predictiveα-decay halflives for theα-decay chains of ^(293,294)119 and ^(294,295)120 are obtained using the DDCM+model,and the theoretical halflives of the spontaneous fission andβ-decay for these nuclides are also presented.[Conclusions]For theα-decay chains of^(293,294)119 and^(294,295)120,α-decay is predicted to be the dominant decay mode for most of the nuclei,while the half-lives of spontaneous fission andβ-decay are predicted to be comparable to those of theα-decay near the region of A=261.We expect that these results will serve as a useful reference for the synthesis of new isotopes in the future.

关 键 词：α 衰变 自发裂变 超重核 半衰期 

分 类 号：O571.321[理学—粒子物理与原子核物理]