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Theoretical predictions on cluster radioactivity of superheavy nuclei with Z=119,120

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Chinese Physics C 2024年第1期48卷 125-137页

作者：刘洁洁王震张涵韬任中洲 School of Physics Science and Engineering Tongji UniversityShanghai 200092China Key Laboratory of Advanced Micro-Structure Materials Ministry of EducationShanghai 200092China

In this study,we investigate the cluster radioactivity(CR)of new superheavy elements with Z=119 and 120 based on two successful theoretical methods with modified parameters:the density-dependent cluster model(DDCM)and unified decay formula(UDF).First,we employ the DDCM and UDF to accurately reproduce the experimental half-lives of cluster emissions,which demonstrates the high reliability of our theoretical methods.Then,we systematically predict the probable cluster modes of ^(293-311)119 and ^(293-302)120 as well as their corresponding decay energies and half-lives.The half-lives of cluster decay derived from the DDCM are consistent with those from the UDF.Therefore,our results reveal that the cluster emission of ^(8)Be,emitted from the Z=119 and 120 isotopic chains,exhibits the minimum half-life for cluster emission,and hence,^(8)Be emission is considered the most probable cluster decay mode.Moreover,we explore the competition betweenαdecay and CR and find thatαdecay may be the dominant decay mode against CR.Furthermore,the good linear relationship between the decay energy and the number ofαparticles within the emitted cluster is extended to the range of superheavy nuclei(SHN).We anticipate that our theoretical predictions for CR will provide valuable references for the experimental synthesis of new SHN.

关键词： cluster radioactivity superheavy nuclei density-dependent cluster model

Research onα-decay for the superheavy nuclei with Z=118-120

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Chinese Physics C 2022年第5期46卷 116-128页

作者：何晨牛中明包小军郭建友 School of Physics and Optoelectronics Engineering Anhui UniversityHefei 230601China Department of Physics Hunan Normal UniversityChangsha 410081China

The generalized liquid-drop model(GLDM)with the microscopic shell correction from relativistic Hartree-Fock(RHF)calculations is used to explore theα-decay of superheavy nuclei.The known nuclei with Z=106−118 are chosen as examples for testing.The calculated half-lives ofα-decay agree with the experimental data better than those from the GLDM with the shell correction in the Weizsa¨cker-Skyrme model.Moreover,the influence of the decay energy Q_(α) onα-decay is investigated.It is determined that the Q_(α) values obtained from the WS4 model with radial basis function(RBF)correction match the experimental data optimally.Owing to these advantages,the GLDM with the RHF shell correction and WS4+RBF Q_(α) values is adopted to predict theα-decay lifetime for the unknown superheavy nuclei with Z=118−120.The trend of the availableα-decay half-lives according to the neutron number is similar to the trends of the values from the GLDM calculation without shell correction as well as the universal decay law(UDL)formula.Comparably,the RHF shell correction depresses(raises)theα-decay lifetime for most nuclei with N186).In comparison with the half-lives of spontaneous fission,it can be concluded that theα-decay is dominant in the superheavy nuclei ^(281−304)118,^(284−306)119,and ^(287−308)120.These results are beneficial to the exploration of superheavy nuclei in experiments.

关键词： generalized liquid-drop model α-decay superheavy nuclei relativistic Hartree-Fock WS4 model

Systematics on production of superheavy nuclei Z=119-122 in fusion-evaporation reactions

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Nuclear Science and Techniques 2021年第10期32卷 59-71页

作者： Fei Niu Peng-Hui Chen Zhao-Qing Feng School of Physics and Optoelectronic Technology South China University of TechnologyGuangzhou 510640China College of Electrical Energy and Power Engineering Yangzhou UniversityYangzhou 225000China

The fusion dynamics of the formation of super-heavy nuclei were investigated thoroughly within the din-uclear system model.The Monte Carlo approach was implemented in the nucleon transfer process to include all possible orientations,at which the dinuclear system is assumed to be formed at the touching configuration of dinuclear fragments.The production cross sections of superheavy nuclei Cn,Fl,Lv,Ts,and Og were calculated and compared with the available data from Dubna.The evaporation residue excitation functions in the channels of pure neutrons and charged particles were systematically analyzed.The combinations of 44 Sc,48;50 Ti,49;51 V,52;54 Cr,58;62 Fe,and 62;64 Ni bombarding the actinide nuclides 238 U,244 Pu,248 Cm,247;249 Bk,249;251 Cf,252 Es,and 243 Am were calculated to produce the superheavy elements with Z¼119?122.We obtained that the production cross sections sensitively depend on the neutron richness of the reaction system.The structure of the evaporation residue excitation function is related to the neutron separation energy and fission barrier of the compound nucleus.

关键词： Dinuclear system model Fusion-evaporation reactions superheavy nuclei Cross sections

α-decay half-lives of superheavy nuclei and general predictions

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Chinese Physics C 2009年第8期33卷 633-638页

作者：董建敏张鸿飞王艳召左维苏昕宁李君清 School of Nuclear Science and Technology Lanzhou University Institute of Modern Physics Chinese Academy of Sciences

The generalized liquid drop model （GLDM） and the cluster model have been employed to calculate the α-decay half-lives of superheavy nuclei （SHN） using the experimental α-decay Q values. The results of the cluster model are slightly poorer than those from the GLDM if experimental Q values are used. The prediction powers of these two models with theoretical Q values from Audi et al. （QAudi） and Muntian et al. （QM） have been tested to find that the cluster model with QAudi and QM could provide reliable results for Z 〉 112 but the GLDM with QAudi for Z 112. The half-lives of some still unknown nuclei are predicted by these two models and these results may be useful for future experimental assignment and identification.

关键词： superheavy nuclei α-decay half-lives generalized liquid drop model cluster model

Evaporation residue cross sections of superheavy nuclei based on optimized nuclear data

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Chinese Physics C 2023年第12期47卷 124-130页

作者：李佳星张鸿飞 School of Physics Xi’an Jiaotong UniversityXi’an 710049China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China

This study proposes an optimized method for estimating atomic nucleus masses by combining the finiterangedroplet model (FRDM) with the support vector machine algorithm. The optimization process significantly improvesthe accuracy of the FRDM by reducing the root mean square error from 0.606 to 0.253 MeV. The optimizedmass data obtained from this method are then used to calculate the evaporation residue cross-sections (ERCSs) forfusion-evaporation reactions, employing the di-nuclear system model. The experimental results for the 48Ca+238U reactionare relatively well reproduced using these optimized mass data. Additionally, the study investigates the impactof mass uncertainties on fusion and survival probabilities. By considering the mass uncertainties, the ERCSs fornew elements 119 and 120 are predicted based on the obtained optimized mass data.

关键词： superheavy nuclei SVM algorithm DNS model evaporation residue cross-sections

Microscopic study of higher-order deformation effects on the ground states of superheavy nuclei around^(270)Hs

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Chinese Physics C 2022年第2期46卷 140-148页

作者：王晓倩孙向向周善贵 CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of ScienceBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China

We investigate the effects of higher-order deformations β_(λ)(λ=4,6,8,and 10)on the ground state prop-erties of superheavy nuclei(SHN)near the doubly magic deformed nucleus ^(270)Hs using the multidimensionally-con-strained relativistic mean-field(MDC-RMF)model with five effective interactions:PC-PK1,PK1,NL3^(+),DD-ME2,and PKDD.The doubly magic properties of ^(270)Hs include large energy gaps at N=162 and Z=108 in the single-particle spectra.By investigating the binding energies and single-particle levels of ^(270)Hs in the multidimensional de-formation space,we find that,among these higher-order deformations,the deformationβ6 has the greatest impact onthe binding energy and influences the shell gaps considerably.Similar conclusions hold for other SHN near ^(270)Hs.Our calculations demonstrate that the deformation β_(6) must be considered when studying SHN using MDC-RMF.

关键词： density functional theory superheavy nuclei deformation effects

Competition between α-decay and β-decay for heavy and superheavy nuclei

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Chinese Physics C 2014年第12期38卷 16-24页

作者：圣宗强舒良萍孟影胡继刚钱建发 School of Science Anhui University of Science and Technology School of Electronic Science and Applied Physics Hefei University of Technology

In this work, the β-stable region for Z ≥90 is proposed based on a successful binding energy formula.The calculated β-stable nuclei in the β-stable region are in good agreement with the ones obtained by Mo¨ller et al. The half-lives of the nuclei close to the β-stable region are calculated and the competition between α-decay andβ-decay is systematically investigated. The calculated half-lives and the suggested decay modes are well in line with the experimental results. The decay modes are mostly β--decay above the β-stable region. Especially for Z ≤111,all the decay modes are β--decay. Regarding the nuclei above the β-stable region, α-decay and β--decay（α＋β-）can occur simultaneously when Z≥ 112. This is a very interesting phenomenon. The competition between α-decay and β-decay is very complex and drastic below the β-stable region. The predictions for half-lives and decay modes of the nuclei with Z =107–110 are presented in detail.

关键词： decay β-stable region half-life superheavy nuclei

Prediction of synthesis cross sections of new moscovium isotopes in fusion‑evaporation reactions

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Nuclear Science and Techniques 2023年第1期34卷 86-101页

作者： Peng‑Hui Chen Hao Wu Zu‑Xing Yang Xiang‑Hua Zeng Zhao‑Qing Feng School of Physical Science and Technology Yangzhou UniversityYangzhou 225009China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China RIKEN Nishina Center WakoSaitama 351‑0198Japan College of Electrical Power and Energy EngineeringYangzhou UniversityYangzhou 225009China School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510641China

In the framework of the dinuclear system model,the synthesis mechanism of the superheavy nuclides with atomic numbers Z=112,114,115 in the reactions of projectiles 40,^(48)Ca bombarding on targets^(238)U,^(242)Pu,and^(243)Am within a wide interval of incident energy has been investigated systematically.Based on the available experimental excitation functions,the dependence of calculated synthesis cross-sections on collision orientations has been studied thoroughly.The total kinetic energy(TKE)of these collisions with fixed collision orientation shows orientation dependence,which can be used to predict the tendency of kinetic energy diffusion.The TKE is dependent on incident energies,as discussed in this paper.We applied the method based on the Coulomb barrier distribution function in our calculations.This allowed us to approximately consider all the collision orientations from tip-tip to side-side.The calculations of excitation functions of^(48)Ca+^(238)U,^(48)Ca+242Pu,and^(48)Ca+^(243)Am are in good agreement with the available experimental data.The isospin effect of projectiles on production cross-sections of moscovium isotopes and the influence of the entrance channel effect on the synthesis cross-sections of superheavy nuclei are also discussed in this paper.The synthesis cross-section of new moscovium isotopes 278−286 Mc was predicted to be as large as hundreds of pb in the fusion-evaporation reactions of^(35,37)Cl+^(248)Cf,^(38,40)Ar+^(247)Bk,^(39,41)K+247 Cm,^(40,42,44,46)Ca+^(243)Am,45 Sc+^(244)Pu,and^(46,48,50)Ti+237Np,51 V+^(238)U at some typical excitation energies.

关键词： Dinuclear system model superheavy nuclei Complete fusion reactions Production cross-section

Systematic study of α decay half-lives for even–even nuclei within a deformed two-potential approach

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Communications in Theoretical Physics 2022年第5期74卷 86-96页

作者：桂海峰刘宏铭吴喜军初鹏程何彪李小华 School of Nuclear Science and Technology University of South China421001 HengyangChina School of Math and Physics University of South China421001 HengyangChina The Research Center for Theoretical Physics Science SchoolQingdao University of TechnologyQingdao 266033China College of Physics and Electronics Central South UniversityChangsha 410083 China National Exemplary Base for International Sci&Tech.Collaboration of Nuclear Energy and Nuclear Safety University of South ChinaHengyang 421001 China Cooperative Innovation Center for Nuclear Fuel Cycle Technology&Equipment University of South China421001 Hengyang.China Key Laboratory of Low Dimensional Quantum Structures and Quantum Control Hunan Normal University

In this work,we systematically study theαdecay half-lives of 196 even–even nuclei using a two-potential approach improved by considering nuclear deformation.The results show that the accuracy of this model has been improved after considering nuclear deformation.In addition,we extend this model to predict theαdecay half-lives of Z=118 and 120 isotopes by inputting theαdecay energies extracted from the Weizsacker–Skyrme-type(WS-type)mass model,a simple nuclear mass formula,relativistic continuum Hartree–Bogoliubov theory and Duflo-Zuker-19(DZ19)mass model.It is useful for identifying the new superheavy elements or isotopes for future experiments.Finally,the predictedαdecay energies and half-lives of Z=118 and 120isotopes are analyzed,and the shell structure of superheavy nuclei is discussed.It shows that the shell effect is obvious at N=184,while the shell effect at N=178 depends on the nuclear mass model.

关键词： α-decay deformed two-potential approach superheavy nuclei magic number