We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-...We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-2(SHANS2),a gas-filled recoil separator located at the China Accelerator Facility for Superheavy Elements(CAFE2).In total,20 decay chains are attributed to ^(288)Mc and 1 decay chain is assigned to ^(287)Mc.The measured oa-decay properties of ^(287,288)Mc as well as its descendants are consistent with the known data.No additional decay chains originating from the 2n or 5n reaction channels were detected.The excitation function of the ^(243)Am(^(48)Ca,3n)^(288)Mc reaction was measured at the cross-section level of picobarn,which indicates the promising capability for the study of heavy and superheavy nuclei at the facility.展开更多
Man-made superheavy elements(SHE)are produced as energetic recoils in complete-fusion reactions and need to be thermalized in a gas-filled chamber for chemical studies.The ever-shorter half-lives and decreasing produc...Man-made superheavy elements(SHE)are produced as energetic recoils in complete-fusion reactions and need to be thermalized in a gas-filled chamber for chemical studies.The ever-shorter half-lives and decreasing production rates of the elements beyond Fl(atomic number Z=114)-the heaviest element chemically studied today-require the development of novel techniques for quantitative thermalization and fast extraction efficiency.The Universal high-density gas stopping Cell(UniCell),currently under construction,was proposed to achieve this.Within this work,we propose an Ion Transfer by Gas Flow(ITGF)device,which serves as a UniCell ejector to interface with a gas chromatography detector array for chemical studies.Detailed parameter optimizations,using gas dynamics and Monte Carlo ion-trajectory simulations,promise fast(within a few ms)and highly efficient(up to 100%)ion extraction across a wide mass range.These ions can then be transmitted quantitatively through the ITGF into the high-pressure environment needed for further chemical studies.展开更多
The synthesis of superheavy nuclei remains a critical area of research in nuclear physics,with the aim of extending the periodic table and deepening our understanding of the properties of nuclei.This review provides a...The synthesis of superheavy nuclei remains a critical area of research in nuclear physics,with the aim of extending the periodic table and deepening our understanding of the properties of nuclei.This review provides a comprehensive overview of the latest advancements in superheavy nuclei synthesis,focusing on both the experimental and theoretical developments.We discuss the primary synthesis methods,including early fusion reactions with light nuclei,cold fusion reactions using lead and bismuth targets,and hot fusion reactions involving48Ca projectiles and actinide targets.In addition,we introduce the major experimental facilities and theoretical models currently employed worldwide.This review also summarizes the experimental plans and theoretical predictions for the synthesis of new superheavy elements.Furthermore,we discuss future directions,including the potential of employing heavier projectiles,radioactive beam-induced reactions,and multi-nucleon transfer reactions,which may offer new pathways for discovering unknown superheavy nuclei.展开更多
This paper provides a comprehensive analysis of all stages of the heavy-ion fusion evaporation reaction,aiming to enhance the understanding of the entire process and identify the influencing factors in calculating the...This paper provides a comprehensive analysis of all stages of the heavy-ion fusion evaporation reaction,aiming to enhance the understanding of the entire process and identify the influencing factors in calculating the evaporation residue cross-section.By focusing on the synthesis of superheavy nuclei with Z=114,we discuss the capture cross-section,fusion probability,and survival probability of the ^(48)Ca+^(244)Pu reaction and compare them with those of the 40Ar+248Cm reaction.Moreover,a systematic study examined the evaporation residue cross-sections for the synthesis of superheavy nuclei with Z=112-116 using ^(40)Ar as the projectile nucleus.The results indicate that utilizing ^(40)Ar as the projectile nucleus for synthesizing isotopes with Z=114 offers advantages such as lower incident energy and reduced experimental costs.Furthermore,using ^(40)Ar as the projectile nucleus enables the synthesis of a new key isotope,285115,thereby facilitating its identification.展开更多
In order to study the influence of the shell effects on the formation and fission of superheavy elements, we applied multidimensional Langevin equations. The evaporation residue cross sections have been calculated for...In order to study the influence of the shell effects on the formation and fission of superheavy elements, we applied multidimensional Langevin equations. The evaporation residue cross sections have been calculated for 3n, 4n, and 5n evaporation channels using three(K = 0)-and four(K ≠ 0)-dimensional Langevin equations. Calculations were done for ^(48)Ca + ^(238)U and ^(48)Ca + ^(244)Pu hot fusion reactions with 3n, An evaporation channels and ^(70)Zn+ ^(208)Pb, and ^(54)Cr + ^(209)Bi cold fusion reactions with In and 2n evaporation channels. The calculations were performed for An and 5n evaporation channels of the ^(26)Mg+ ^(238)U reaction, as well. Our results show that with increasing dimension of Langevin equations the residue cross section increases, whereas the fission cross section decreases. The obtained results with four-dimensional Langevin and considering shell effects are in better agreement with experimental data in comparison with three-and four-dimensional Langevin equations without shell effects.展开更多
Information on the decay process of nuclides in the superheavy region is critical in investigating new elements beyond oganesson and the island of stability.This paper presents the application of a random forest algor...Information on the decay process of nuclides in the superheavy region is critical in investigating new elements beyond oganesson and the island of stability.This paper presents the application of a random forest algorithm to examine the competition among different decay modes in the superheavy region,includingα decay,β^(-)decay,β^(+)decay,electron capture and spontaneous fission.The observed half-lives and dominant decay mode are well reproduced.The dominant decay mode of 96.9%of the nuclei beyond ^(212) Po is correctly obtained.Further,α decay is predicted to be the dominant decay mode for isotopes in new elements Z=119-122,except for spontaneous fission in certain even–even elements owing to the increased Coulomb repulsion and odd–even effect.The predicted half-lives demonstrate the existence of a long-lived spontaneous fission island southwest of ^(298) Fl caused by the competition between the fission barrier and Coulomb repulsion.A better understanding of spontaneous fission,particularly beyond ^(286)Fl,is crucial in the search for new elements and the island of stability.展开更多
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 possib...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.展开更多
Abstract The effects of mass asymmetry on the production of superheavy nuclei(SHN),within the dinuclear system model,are investigated in this study.It is observed that the fusion probability decreases with decreasing ...Abstract The effects of mass asymmetry on the production of superheavy nuclei(SHN),within the dinuclear system model,are investigated in this study.It is observed that the fusion probability decreases with decreasing mass asymmetry.A total of 192 possible combinations of projectiles from O to Ti and targets with half-lives longer than30 days for producing SHN^(264)Db,^(265)Db,^(267)Sg,^(268)Bh,268Sg,^(269)Bh,^(271)Hs,^(271)Mt,^(272)Hs,^(272)Mt,^(273)Mt,^(274)Ds,275Ds,^(275)Rg,^(276)Ds,^(276)Rg,^(277)Rg,^(278)Cn,^(279)Cn,and^(280)Cn are examined.Further,the optimal combinations and incident energies for synthesizing these nuclei are predicted.Most of the cross sections for production of SHNare larger than 10 pb;therefore,the process can be carried out with the available experimental equipment.展开更多
Based on the dinuclear system model,the calculated evaporation residue cross sections matched well with the current experimental results.The synthesis of superheavy elements Z=121 was systematically studied through co...Based on the dinuclear system model,the calculated evaporation residue cross sections matched well with the current experimental results.The synthesis of superheavy elements Z=121 was systematically studied through combinations of stable projectiles with Z=21-30 and targets with half-lives exceeding 50 d.The influence of mass asymmetry and isotopic dependence on the projectile and target nuclei was investigated in detail.The reactions^(254)Es(^(46)Ti,3n)^(297)121 and^(252)Es(^(46)Ti,3n)^(295)121 were found to be experimentally feasible for synthesizing superheavy element Z=121,with maximal evaporation residue cross sections of 6.619 and 4.123 fb at 219.9 and 223.9 MeV,respectively.展开更多
The α-decay half-lives of a set of superheavy nuclear isotope chain from Z = 105 to 120 have been analyzed systematically within the WKB method, and some nuclear structure features are found. The decay barriers have ...The α-decay half-lives of a set of superheavy nuclear isotope chain from Z = 105 to 120 have been analyzed systematically within the WKB method, and some nuclear structure features are found. The decay barriers have been determined in the quasi-molecular shape path within the Generalized Liquid Drop Model （GLDM） including the proximity effects between nucleons in a neck and the mass and charge asymmetry. The results are in reasonable agreement with the published experimental data for the alpha decay half-llves of isotopes of charge 112, 114, and 116, of the element 294118 and of some decay products. A comparison of present calculations with the results by the DDM3Y effective interaction and by the Viola-Seaborg-Sobiczewski （VSS） formulae is also made. The experimental a decay half lives all stand in between the GLDM calculations and VSS formula results. This demonstrates the possibility of these models to provide reasonable estimates for the half-lives of nuclear decays by a emissions for the domain of SHN. The half-lives of these new nuclei are thus well tested from the reasonable consistence of the macroscopic, the microscopic, the empirical formulae and the experimental data. This also shows that the present data of SHN themselves are consistent. It could suggest that the present experimental claims on the existence of new elements Z =110 - 118 are reliable. It is expected that greater deviations of a few SHN between the data and the model may be eliminated by further improvements on the precision of the measurements.展开更多
The ground state properties of superheavy nuclei are systematically calculated by the macroscopic-microscopic (MM) model with the Nilsson potential.The calculations well produced the ground state binding energies,α-d...The ground state properties of superheavy nuclei are systematically calculated by the macroscopic-microscopic (MM) model with the Nilsson potential.The calculations well produced the ground state binding energies,α-decay energies,and half lives of superheavy nuclei.The calculated results are systematically compared with availableexperimental data.The calculated results are also compared with theoretical results from other MM models and fromrelativistic mean-field model.The calculations and comparisons show that the MM model is reliable in superheavy regionand that the MM model results are not very sensitive to the choice of microscopic single-particle potential.展开更多
Configuration-constrained calculations of potential-energy surfaces for ^292 122 show the occurrence of multiquasiparticle high-K isomeric state at oblate superdeformation. Such state could play a unique role in super...Configuration-constrained calculations of potential-energy surfaces for ^292 122 show the occurrence of multiquasiparticle high-K isomeric state at oblate superdeformation. Such state could play a unique role in superheavy nuclei, with possible long life time from enhanced difficulty in fission due to additional barrier at oblate deformation, retardation in a decay due to unpaired nucleons, and hindrance in γ-ray transition due to K forbiddenness.展开更多
From the point of view of the interplay between order and chaos, the most regular single-particle motion of neutrons has been found in the superheavy system with and based on the Skyrme–Hartree–Fock model and in t...From the point of view of the interplay between order and chaos, the most regular single-particle motion of neutrons has been found in the superheavy system with and based on the Skyrme–Hartree–Fock model and in the system with and based on the relativistic mean-field model. It has been shown that the statistical analysis of spectra can give valuable information about the stability of suprheavy systems. In addition it may yield deep insight into the single-particle motion in the mean field formed by the superheavy system.展开更多
Q value and optimal exciting energy of hypothetical superheavy nuclei in cold fusion reaction are calculated with relativistic mean field model and semiemperical shell model mass equation(SSME)and the validity of the ...Q value and optimal exciting energy of hypothetical superheavy nuclei in cold fusion reaction are calculated with relativistic mean field model and semiemperical shell model mass equation(SSME)and the validity of the two models is tested.To give useful references for the experiments in the superheavy nuclei synthesized in cold fusion reactions,the Q value,fusion barrier and optimal exciting energy for the possible target plus projectile combinations suggested by Gupta et al.are calculated and the most possible target plus projectile combinations are pointed out according to our calculations.展开更多
In the current study,we examined every possible cluster-daughter combination in the heavy-particle decay of isotopes ^(297-300)119 and computed the decay half-lives using the modified generalized liquid drop model(MGL...In the current study,we examined every possible cluster-daughter combination in the heavy-particle decay of isotopes ^(297-300)119 and computed the decay half-lives using the modified generalized liquid drop model(MGLDM)with the preformation factor depending on the disintegration energy.The predicted half-life of every heavy cluster(Z_(C)≥32)was within the experimentally observable limits.These results aligned with the predictions of Poenaru et al.[Phys.Rev.Lett.107,062503(2011)]that superheavy nuclei(SHN)with Z>110 will release heavy particles with a penetrability comparable to or greater than theα-decay.The half-lives predicted using the MGLDM for clusters^(89)Rb,^(91)Rb,and^(92)Rb from parents^(297)119,^(299)119,and^(300)119,respectively,agreed with the predictions of Poenaru et al.[Eur.Phys.J.A 54,14(2018)].It was found that the isotopes of heavy clusters Kr,Rb,Sr,Pa,In,and Cd had half-lives comparable to theαhalf-life;and isotopes of clusters I,Xe,and Cs had the minimum half-life(10^(-14)s).These observations revealed the role of the shell closure(Z=82,N=82,and N=126)of the cluster and daughter nuclei in heavy-cluster radioactivity.We predicted that isotope ^(297,299)119 decayed by 4αdecay chains and isotope^(300)119 decayed by 6αdecay chains,while^(298)119 decayed by continuousαdecay chains.The predicted half-lives and modes of decay of the nuclei in the decay chains of^(297-300)119 agreed with the experimental data,proving the reliability of our calculations.The present study determined the most favorable heavy-cluster emissions from these nuclei and provided suitable projectile-target combinations for their synthesis.展开更多
The excitation functions of two very similar reaction channels, 58Fe＋ 208pb→ 265Hs ＋ 1n and 58Fe＋ 209Bi → 266Mt ＋1n are studied in the framework of the dinuclear system conception. The fusion probabilities are f...The excitation functions of two very similar reaction channels, 58Fe＋ 208pb→ 265Hs ＋ 1n and 58Fe＋ 209Bi → 266Mt ＋1n are studied in the framework of the dinuclear system conception. The fusion probabilities are found to be strongly subject to the structure of the driving potential. Usually the fusion probability is hindered by a barrier from the injection channel towards the compound nuclear configuration. The barrier towards the mass symmetrical direction, however, also plays an important role for the fusion probability, because the barrier hinders the quasi-fission, and therefore helps fusion.展开更多
Based on the liquid-drop model and using the first derivative of the normalized Gaussian function to consider the shell correction,a simpleα-decay energy formula is proposed for heavy and superheavy nuclei.The values...Based on the liquid-drop model and using the first derivative of the normalized Gaussian function to consider the shell correction,a simpleα-decay energy formula is proposed for heavy and superheavy nuclei.The values of corresponding adjustable parameters are obtained by fittingα-decay energies of 209 nuclei ranging from Z=90 to Z=118 with N≥140.The calculated results are in good agreement with the experimental data.The average and standard deviations between the experimental data and theoretical results are 0.141 and 0.190 Me V,respectively.For comparison,the reliable formulae proposed by Dong T K et al(2010,Phys.Rev.C 82,034320),Dong J M et al(2010,Phys.Rev.C 81,064309)and the WS3+nuclear mass model proposed by Wang N et al(2011,Phys.Rev.C 84,051303)are also used.The results indicate that our improved 7-parameter formula is superior to these empirical formulae and is largely consistent with the WS3+nuclear mass model.In addition,we extend this formula to predict theα-decay energies for nuclei with Z=117,118,119 and 120.The predicted results of these formulae are basically consistent.展开更多
A proposal for an experiment to measure the cross section of antiproton production in a proton-nuclear collision in a kinematically forbidden region for nucleon-nucleon interaction on a fixed LHC target is considered....A proposal for an experiment to measure the cross section of antiproton production in a proton-nuclear collision in a kinematically forbidden region for nucleon-nucleon interaction on a fixed LHC target is considered. It is shown that this process can be separated from the kinematically allowed production process using the existing detectors of the ALICE facility at a proton energy of 7 TeV with a fixed nuclear target. Assuming the scale dependence of the cross section, the data obtained can be used to estimate the subthreshold cross section for the production of superheavy particles with a mass of several tens of TeV in the LHC lead nucleus beam.展开更多
The latest experimental data ofα-decay half-lives for 573 nuclei within the range of 52≤Z≤118 are utilized to enhance empirical formulas with updated coefficients.These formulas are enhanced by analyzing the contri...The latest experimental data ofα-decay half-lives for 573 nuclei within the range of 52≤Z≤118 are utilized to enhance empirical formulas with updated coefficients.These formulas are enhanced by analyzing the contributions of orbital angular momentum and isospin asymmetry.The effect of deformation of daughter nuclei on theα-decay half-life is modeled by incorporating two additional terms,dependent on the quadrupole and hexadecapole deformation parameters,into the empirical formulas for a-decay half-lives.Incorporating these deformation-dependent terms,along with angular momentum and isospin asymmetry,we improve the standard deviation by approximately 17%.The revised empirical formulas for aα-decay half-lives demonstrate better agreement with experimental data when deformation factors are included.The modified formulas are validated through comparisons with recent experimental results and further theoretical predictions.This paper presents and compares a-decay half-life predictions for several isotopes of superheavy nuclei with Z=120-126,which are yet to be experimentally synthesized.For various isotopes of each element,the variation in logio T with changes in the neutron number is also explored.展开更多
In this study,the accuracy of the Finite-Range Droplet Model 2012(FRDM)in describing theαdecay energies of the 947 known heavy and superheavy nuclei is investigated.We find evident discrepancies between theαdecay en...In this study,the accuracy of the Finite-Range Droplet Model 2012(FRDM)in describing theαdecay energies of the 947 known heavy and superheavy nuclei is investigated.We find evident discrepancies between theαdecay energies obtained using the FRDM and those reported by the evaluated atomic mass table AME 2020(AME).In particular,the FRDM underestimates the experimentalαdecay energies of superheavy nuclei.Theαdecay energies of known nuclei obtained using the FRDM are optimized using a neural network approach,i.e.,FRDM-NN,and the accuracy improves significantly.Theαdecay energy systematics obtained using both the FRDM and FRDM-NN exhibit an evident shell effect at neutron number N=184,implying that N=184 may be the magic number of the superheavy nucleus region.Theαdecay half-lives of known superheavy nuclei are calculated using the Generalized Liquid Drop Model(GLDM)and Royer formula with the input of the optimizedαdecay energies obtained using the FRDM-NN,and the calculations can reproduce the experimental data well.Theαdecay half-lives of unknown superheavy nuclei,in particular,superheavy nuclei with Z=119 and 120,are also predicted using the GLDM and Royer formula with the input of theαdecay energy obtained using the FRDM-NN.The relative error of two types of predictedαdecay half-lives and superposition are analyzed,and the average predictions are given.Theαdecay energies predicted by the FRDM-NN and theαdecay half-lives calculated using the GLDM and Royer formula can provide references for the experimental synthesis of new superheavy elements with Z=119 and120.展开更多
基金supported in part by the National Key R&D Program of China (Contract Nos.2023YFA1606500,2024YFE0109800,and 2024YFE0110400)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB34010000)+5 种基金the Gansu Key Project of Science and Technology (Grant No.23ZDGA014)the Guangdong Major Project of Basic and Applied Basic Research (Grant No.2021B0301030006)the National Natural Science Foundation of China (Grant Nos.12105328,W2412040,12475126,12422507,12035011,12375118,12435008,and W2412043)the Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.YSBR-002)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant Nos.2020409 and 2023439)the Russian Science Foundation (Grant No.25-42-00003)。
文摘We report the results of the experiment on synthesizing ^(287,288)Mc isotopes (Z=115) using the fusionevaporation reaction ^(243)Am(^(48)Ca,4n,3n)^(287,288)Mc at the Spectrometer for Heavy Atoms and Nuclear Structure-2(SHANS2),a gas-filled recoil separator located at the China Accelerator Facility for Superheavy Elements(CAFE2).In total,20 decay chains are attributed to ^(288)Mc and 1 decay chain is assigned to ^(287)Mc.The measured oa-decay properties of ^(287,288)Mc as well as its descendants are consistent with the known data.No additional decay chains originating from the 2n or 5n reaction channels were detected.The excitation function of the ^(243)Am(^(48)Ca,3n)^(288)Mc reaction was measured at the cross-section level of picobarn,which indicates the promising capability for the study of heavy and superheavy nuclei at the facility.
基金This work was supported by the German BMBF (No.05P21UMFN2)
文摘Man-made superheavy elements(SHE)are produced as energetic recoils in complete-fusion reactions and need to be thermalized in a gas-filled chamber for chemical studies.The ever-shorter half-lives and decreasing production rates of the elements beyond Fl(atomic number Z=114)-the heaviest element chemically studied today-require the development of novel techniques for quantitative thermalization and fast extraction efficiency.The Universal high-density gas stopping Cell(UniCell),currently under construction,was proposed to achieve this.Within this work,we propose an Ion Transfer by Gas Flow(ITGF)device,which serves as a UniCell ejector to interface with a gas chromatography detector array for chemical studies.Detailed parameter optimizations,using gas dynamics and Monte Carlo ion-trajectory simulations,promise fast(within a few ms)and highly efficient(up to 100%)ion extraction across a wide mass range.These ions can then be transmitted quantitatively through the ITGF into the high-pressure environment needed for further chemical studies.
基金supported by the National Key R&D Program of China(No.2023YFA1606401)the National Key R&D Program of China(Nos.2023YFA1606500,2023YFA1606501,2023YFA1606504)+3 种基金the National Natural Science Foundation of China(Nos.12135004,11635003,11961141004,12375118,and 12435008)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB34010000)the Major State Basic Research Development Program of China(2023YFA1606503)the CAS Strategic Priority Research Program(XDB34010000)。
文摘The synthesis of superheavy nuclei remains a critical area of research in nuclear physics,with the aim of extending the periodic table and deepening our understanding of the properties of nuclei.This review provides a comprehensive overview of the latest advancements in superheavy nuclei synthesis,focusing on both the experimental and theoretical developments.We discuss the primary synthesis methods,including early fusion reactions with light nuclei,cold fusion reactions using lead and bismuth targets,and hot fusion reactions involving48Ca projectiles and actinide targets.In addition,we introduce the major experimental facilities and theoretical models currently employed worldwide.This review also summarizes the experimental plans and theoretical predictions for the synthesis of new superheavy elements.Furthermore,we discuss future directions,including the potential of employing heavier projectiles,radioactive beam-induced reactions,and multi-nucleon transfer reactions,which may offer new pathways for discovering unknown superheavy nuclei.
基金supported by the National Natural Science Foundation of China(Nos.12175170 and 11675066).
文摘This paper provides a comprehensive analysis of all stages of the heavy-ion fusion evaporation reaction,aiming to enhance the understanding of the entire process and identify the influencing factors in calculating the evaporation residue cross-section.By focusing on the synthesis of superheavy nuclei with Z=114,we discuss the capture cross-section,fusion probability,and survival probability of the ^(48)Ca+^(244)Pu reaction and compare them with those of the 40Ar+248Cm reaction.Moreover,a systematic study examined the evaporation residue cross-sections for the synthesis of superheavy nuclei with Z=112-116 using ^(40)Ar as the projectile nucleus.The results indicate that utilizing ^(40)Ar as the projectile nucleus for synthesizing isotopes with Z=114 offers advantages such as lower incident energy and reduced experimental costs.Furthermore,using ^(40)Ar as the projectile nucleus enables the synthesis of a new key isotope,285115,thereby facilitating its identification.
文摘In order to study the influence of the shell effects on the formation and fission of superheavy elements, we applied multidimensional Langevin equations. The evaporation residue cross sections have been calculated for 3n, 4n, and 5n evaporation channels using three(K = 0)-and four(K ≠ 0)-dimensional Langevin equations. Calculations were done for ^(48)Ca + ^(238)U and ^(48)Ca + ^(244)Pu hot fusion reactions with 3n, An evaporation channels and ^(70)Zn+ ^(208)Pb, and ^(54)Cr + ^(209)Bi cold fusion reactions with In and 2n evaporation channels. The calculations were performed for An and 5n evaporation channels of the ^(26)Mg+ ^(238)U reaction, as well. Our results show that with increasing dimension of Langevin equations the residue cross section increases, whereas the fission cross section decreases. The obtained results with four-dimensional Langevin and considering shell effects are in better agreement with experimental data in comparison with three-and four-dimensional Langevin equations without shell effects.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research under Grant No. 2021B0301030006the computational resources from SYSU and the National Supercomputer Center in Guangzhou。
文摘Information on the decay process of nuclides in the superheavy region is critical in investigating new elements beyond oganesson and the island of stability.This paper presents the application of a random forest algorithm to examine the competition among different decay modes in the superheavy region,includingα decay,β^(-)decay,β^(+)decay,electron capture and spontaneous fission.The observed half-lives and dominant decay mode are well reproduced.The dominant decay mode of 96.9%of the nuclei beyond ^(212) Po is correctly obtained.Further,α decay is predicted to be the dominant decay mode for isotopes in new elements Z=119-122,except for spontaneous fission in certain even–even elements owing to the increased Coulomb repulsion and odd–even effect.The predicted half-lives demonstrate the existence of a long-lived spontaneous fission island southwest of ^(298) Fl caused by the competition between the fission barrier and Coulomb repulsion.A better understanding of spontaneous fission,particularly beyond ^(286)Fl,is crucial in the search for new elements and the island of stability.
基金This work was supported by the National Natural Science Foundation of China(Nos.12175072 and 11722546)the Talent Program of South China University of Technology.
文摘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.
基金supported by the National Natural Science Foundation of China under Grant No.11605296the Natural Science Foundation of Guangdong Province,China(Grant No.2016A030310208)the National Natural Science Foundation of China under Grant Nos.11875328,11405278 and 11605270
文摘Abstract The effects of mass asymmetry on the production of superheavy nuclei(SHN),within the dinuclear system model,are investigated in this study.It is observed that the fusion probability decreases with decreasing mass asymmetry.A total of 192 possible combinations of projectiles from O to Ti and targets with half-lives longer than30 days for producing SHN^(264)Db,^(265)Db,^(267)Sg,^(268)Bh,268Sg,^(269)Bh,^(271)Hs,^(271)Mt,^(272)Hs,^(272)Mt,^(273)Mt,^(274)Ds,275Ds,^(275)Rg,^(276)Ds,^(276)Rg,^(277)Rg,^(278)Cn,^(279)Cn,and^(280)Cn are examined.Further,the optimal combinations and incident energies for synthesizing these nuclei are predicted.Most of the cross sections for production of SHNare larger than 10 pb;therefore,the process can be carried out with the available experimental equipment.
基金the National Key R&D Program of China(No.2023YFA1606401)the National Natural Science Foundation of China(Nos.12135004,11635003 and 11961141004).
文摘Based on the dinuclear system model,the calculated evaporation residue cross sections matched well with the current experimental results.The synthesis of superheavy elements Z=121 was systematically studied through combinations of stable projectiles with Z=21-30 and targets with half-lives exceeding 50 d.The influence of mass asymmetry and isotopic dependence on the projectile and target nuclei was investigated in detail.The reactions^(254)Es(^(46)Ti,3n)^(297)121 and^(252)Es(^(46)Ti,3n)^(295)121 were found to be experimentally feasible for synthesizing superheavy element Z=121,with maximal evaporation residue cross sections of 6.619 and 4.123 fb at 219.9 and 223.9 MeV,respectively.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10505016 and 10575119, the Knowledge Innovation Project of the Chinese Academy of Sciences under Grant Nos. KJCX2-SW-N17, KJCX.SYW.N02, Major State Basic Research Development Program under Graalt No. 2007CB815000, and the Financial Support from DFG of Germany tCorresponding author,
文摘The α-decay half-lives of a set of superheavy nuclear isotope chain from Z = 105 to 120 have been analyzed systematically within the WKB method, and some nuclear structure features are found. The decay barriers have been determined in the quasi-molecular shape path within the Generalized Liquid Drop Model （GLDM） including the proximity effects between nucleons in a neck and the mass and charge asymmetry. The results are in reasonable agreement with the published experimental data for the alpha decay half-llves of isotopes of charge 112, 114, and 116, of the element 294118 and of some decay products. A comparison of present calculations with the results by the DDM3Y effective interaction and by the Viola-Seaborg-Sobiczewski （VSS） formulae is also made. The experimental a decay half lives all stand in between the GLDM calculations and VSS formula results. This demonstrates the possibility of these models to provide reasonable estimates for the half-lives of nuclear decays by a emissions for the domain of SHN. The half-lives of these new nuclei are thus well tested from the reasonable consistence of the macroscopic, the microscopic, the empirical formulae and the experimental data. This also shows that the present data of SHN themselves are consistent. It could suggest that the present experimental claims on the existence of new elements Z =110 - 118 are reliable. It is expected that greater deviations of a few SHN between the data and the model may be eliminated by further improvements on the precision of the measurements.
基金National Natural Science Foundation of China under Grant Nos.10125521 and 10535010the State Key Basic Research and Development Program of China under Grant Nos.G2000077400 and 2007CB815004+1 种基金the CAS Knowledge Innovation Project under Grant No.KJCX2-SW-N02the Fund of the Education Ministry of China under Grant No.20010284036
文摘The ground state properties of superheavy nuclei are systematically calculated by the macroscopic-microscopic (MM) model with the Nilsson potential.The calculations well produced the ground state binding energies,α-decay energies,and half lives of superheavy nuclei.The calculated results are systematically compared with availableexperimental data.The calculated results are also compared with theoretical results from other MM models and fromrelativistic mean-field model.The calculations and comparisons show that the MM model is reliable in superheavy regionand that the MM model results are not very sensitive to the choice of microscopic single-particle potential.
基金Supported by the National Natural Science Foundation of China under Grant No.11205120
文摘Configuration-constrained calculations of potential-energy surfaces for ^292 122 show the occurrence of multiquasiparticle high-K isomeric state at oblate superdeformation. Such state could play a unique role in superheavy nuclei, with possible long life time from enhanced difficulty in fission due to additional barrier at oblate deformation, retardation in a decay due to unpaired nucleons, and hindrance in γ-ray transition due to K forbiddenness.
文摘From the point of view of the interplay between order and chaos, the most regular single-particle motion of neutrons has been found in the superheavy system with and based on the Skyrme–Hartree–Fock model and in the system with and based on the relativistic mean-field model. It has been shown that the statistical analysis of spectra can give valuable information about the stability of suprheavy systems. In addition it may yield deep insight into the single-particle motion in the mean field formed by the superheavy system.
基金supported by National Natural Science Foundation of China under Grant No.10275037the Special Research Fund for Doctoral Program of Higher Education of China under Grant No.20010055012
文摘Q value and optimal exciting energy of hypothetical superheavy nuclei in cold fusion reaction are calculated with relativistic mean field model and semiemperical shell model mass equation(SSME)and the validity of the two models is tested.To give useful references for the experiments in the superheavy nuclei synthesized in cold fusion reactions,the Q value,fusion barrier and optimal exciting energy for the possible target plus projectile combinations suggested by Gupta et al.are calculated and the most possible target plus projectile combinations are pointed out according to our calculations.
文摘In the current study,we examined every possible cluster-daughter combination in the heavy-particle decay of isotopes ^(297-300)119 and computed the decay half-lives using the modified generalized liquid drop model(MGLDM)with the preformation factor depending on the disintegration energy.The predicted half-life of every heavy cluster(Z_(C)≥32)was within the experimentally observable limits.These results aligned with the predictions of Poenaru et al.[Phys.Rev.Lett.107,062503(2011)]that superheavy nuclei(SHN)with Z>110 will release heavy particles with a penetrability comparable to or greater than theα-decay.The half-lives predicted using the MGLDM for clusters^(89)Rb,^(91)Rb,and^(92)Rb from parents^(297)119,^(299)119,and^(300)119,respectively,agreed with the predictions of Poenaru et al.[Eur.Phys.J.A 54,14(2018)].It was found that the isotopes of heavy clusters Kr,Rb,Sr,Pa,In,and Cd had half-lives comparable to theαhalf-life;and isotopes of clusters I,Xe,and Cs had the minimum half-life(10^(-14)s).These observations revealed the role of the shell closure(Z=82,N=82,and N=126)of the cluster and daughter nuclei in heavy-cluster radioactivity.We predicted that isotope ^(297,299)119 decayed by 4αdecay chains and isotope^(300)119 decayed by 6αdecay chains,while^(298)119 decayed by continuousαdecay chains.The predicted half-lives and modes of decay of the nuclei in the decay chains of^(297-300)119 agreed with the experimental data,proving the reliability of our calculations.The present study determined the most favorable heavy-cluster emissions from these nuclei and provided suitable projectile-target combinations for their synthesis.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10505016, 10235020, and 10235030, the Knowledge Innovation Project of the Chinese Academy of Sciences under Grant Nos. KJCX2-SW-N17 and KJCX-SYW-N2, the Natural Science Foundation of Guangdong Province under Grant No. 04300874, Major State Basic Research Development Program under Grant No. 2007CB815000 and the Financial Support from DFG of Germany
文摘The excitation functions of two very similar reaction channels, 58Fe＋ 208pb→ 265Hs ＋ 1n and 58Fe＋ 209Bi → 266Mt ＋1n are studied in the framework of the dinuclear system conception. The fusion probabilities are found to be strongly subject to the structure of the driving potential. Usually the fusion probability is hindered by a barrier from the injection channel towards the compound nuclear configuration. The barrier towards the mass symmetrical direction, however, also plays an important role for the fusion probability, because the barrier hinders the quasi-fission, and therefore helps fusion.
基金National Natural Science Foundation of China(Grant No.12175100)the construct program of the key discipline in Hunan province,the Research Foundation of Education Bureau of Hunan Province,China(Grant No.18A237)+1 种基金the Innovation Group of Nuclear and Particle Physics in USC,the Shandong Province Natural Science Foundation,China(Grant No.ZR2022JQ04)the Hunan Provincial Innovation Foundation For Postgraduate(Grant No.CX20210942 and No.CX20220993)
文摘Based on the liquid-drop model and using the first derivative of the normalized Gaussian function to consider the shell correction,a simpleα-decay energy formula is proposed for heavy and superheavy nuclei.The values of corresponding adjustable parameters are obtained by fittingα-decay energies of 209 nuclei ranging from Z=90 to Z=118 with N≥140.The calculated results are in good agreement with the experimental data.The average and standard deviations between the experimental data and theoretical results are 0.141 and 0.190 Me V,respectively.For comparison,the reliable formulae proposed by Dong T K et al(2010,Phys.Rev.C 82,034320),Dong J M et al(2010,Phys.Rev.C 81,064309)and the WS3+nuclear mass model proposed by Wang N et al(2011,Phys.Rev.C 84,051303)are also used.The results indicate that our improved 7-parameter formula is superior to these empirical formulae and is largely consistent with the WS3+nuclear mass model.In addition,we extend this formula to predict theα-decay energies for nuclei with Z=117,118,119 and 120.The predicted results of these formulae are basically consistent.
文摘A proposal for an experiment to measure the cross section of antiproton production in a proton-nuclear collision in a kinematically forbidden region for nucleon-nucleon interaction on a fixed LHC target is considered. It is shown that this process can be separated from the kinematically allowed production process using the existing detectors of the ALICE facility at a proton energy of 7 TeV with a fixed nuclear target. Assuming the scale dependence of the cross section, the data obtained can be used to estimate the subthreshold cross section for the production of superheavy particles with a mass of several tens of TeV in the LHC lead nucleus beam.
文摘The latest experimental data ofα-decay half-lives for 573 nuclei within the range of 52≤Z≤118 are utilized to enhance empirical formulas with updated coefficients.These formulas are enhanced by analyzing the contributions of orbital angular momentum and isospin asymmetry.The effect of deformation of daughter nuclei on theα-decay half-life is modeled by incorporating two additional terms,dependent on the quadrupole and hexadecapole deformation parameters,into the empirical formulas for a-decay half-lives.Incorporating these deformation-dependent terms,along with angular momentum and isospin asymmetry,we improve the standard deviation by approximately 17%.The revised empirical formulas for aα-decay half-lives demonstrate better agreement with experimental data when deformation factors are included.The modified formulas are validated through comparisons with recent experimental results and further theoretical predictions.This paper presents and compares a-decay half-life predictions for several isotopes of superheavy nuclei with Z=120-126,which are yet to be experimentally synthesized.For various isotopes of each element,the variation in logio T with changes in the neutron number is also explored.
基金Supported by the National Natural Science Foundation of China(12405138,12175170)Hubei Provincial Natural Science Foundation of China(2023AFB035)the Natural Science Research Project of Yichang City,China(A23-2-028)。
文摘In this study,the accuracy of the Finite-Range Droplet Model 2012(FRDM)in describing theαdecay energies of the 947 known heavy and superheavy nuclei is investigated.We find evident discrepancies between theαdecay energies obtained using the FRDM and those reported by the evaluated atomic mass table AME 2020(AME).In particular,the FRDM underestimates the experimentalαdecay energies of superheavy nuclei.Theαdecay energies of known nuclei obtained using the FRDM are optimized using a neural network approach,i.e.,FRDM-NN,and the accuracy improves significantly.Theαdecay energy systematics obtained using both the FRDM and FRDM-NN exhibit an evident shell effect at neutron number N=184,implying that N=184 may be the magic number of the superheavy nucleus region.Theαdecay half-lives of known superheavy nuclei are calculated using the Generalized Liquid Drop Model(GLDM)and Royer formula with the input of the optimizedαdecay energies obtained using the FRDM-NN,and the calculations can reproduce the experimental data well.Theαdecay half-lives of unknown superheavy nuclei,in particular,superheavy nuclei with Z=119 and 120,are also predicted using the GLDM and Royer formula with the input of theαdecay energy obtained using the FRDM-NN.The relative error of two types of predictedαdecay half-lives and superposition are analyzed,and the average predictions are given.Theαdecay energies predicted by the FRDM-NN and theαdecay half-lives calculated using the GLDM and Royer formula can provide references for the experimental synthesis of new superheavy elements with Z=119 and120.
