The barrier against the spontaneous fission has been determined within the Generalized Liquid Drop Model （GLDM） including the mass and charge asymmetry, and the proximity energy. The shell correction of the spherica...The barrier against the spontaneous fission has been determined within the Generalized Liquid Drop Model （GLDM） including the mass and charge asymmetry, and the proximity energy. The shell correction of the spherical parent nucleus is calculated by using the Strutinsky method, and the empirical shape-dependent shell correction is 6mp10yed during the deformation process. A quasi-molecular shape sequence has been defined to describe the whole process from one-body shape to two-body shape system, and a two-touching-ellipsoid is adopted when the superdeformed one-body system reaches the rupture point. On these bases the spontaneous fission barriers are systematically studied for nuclei from 2a^Th to 249 Cm for different possible exiting channels with the different mass and charge asymmetries. The double, and triple bumps are found in the fission potential energy in this region, which roughly agree with the experimental results. It is found that at around Sn-like fragment the outer fission barriers are lower, while the partner of the Sn-like fragment is in the range near l^SRu where the ground-state mass is lowered by allowing axially symmetric shapes. The preferable fission channels are distinctly pronounced, which should be corresponding to the fragment mass distributions.展开更多
It is universally acknowledged that the Generalized Liquid Drop Model(GLDM)has two advantages over otherαdecay theoretical models:introduction of the quasimolecular shape mechanism and proximity energy.In the past fe...It is universally acknowledged that the Generalized Liquid Drop Model(GLDM)has two advantages over otherαdecay theoretical models:introduction of the quasimolecular shape mechanism and proximity energy.In the past few decades,the original proximity energy has been improved by numerous works.In the present work,the different improvements of proximity energy are examined when they are applied to the GLDM for enhancing the calculation accuracy and prediction ability ofαdecay half-lives for known and unsynthesized superheavy nuclei.The calculations ofαhalf-lives have systematic improvements in reproducing experimental data after choosing a more suitable proximity energy for application to the GLDM.Encouraged by this,theαdecay half-lives of even-even superheavy nuclei with Z=112-122 are predicted by the GLDM with a more suitable proximity energy.The predictions are consistent with calculations by the improved Royer formula and the universal decay law.In addition,the features of the predictedαdecay half-lives imply that the next double magic nucleus after ^(208)Pb is ^(298)Fl.展开更多
Cluster radioactivity is studied within the generalized liquid drop model(GLDM),in which the shell correction energy,pairing energy,and cluster preformation factor are considered.The calculations show significant impr...Cluster radioactivity is studied within the generalized liquid drop model(GLDM),in which the shell correction energy,pairing energy,and cluster preformation factor are considered.The calculations show significant improvements and can reproduce the experimental data within a factor of 8.04 after considering these physical effects.In addition,the systematic trend of the cluster preformation factors is discussed in terms of the N_(p)N_(n)scheme to study the influence of the valence proton-neutron interaction and shell effect on cluster radioactivity.It is found that log10Pcis linearly related to N_(p)N_(n).This is in agreement with a recent study[L.Qi et al.,Phys.Rev.C 108,014325(2023)],in which log10Pc,obtained using different theoretical models and treatment methods than those used in this study,also had a linear relationship with N_(p)N_(n).Combined with the work by Qi et al.,this study suggests that the linear relationship between log10Pcand N_(p)N_(n)is model-independent and both the shell effect and valence proton-neutron interaction play essential roles in cluster radioactivity.An analytical formula is proposed to calculate the cluster preformation factor based on the N_(p)N_(n)scheme.In addition,the cluster preformation factors and the cluster radioactivity half-lives of some heavy nuclei are predicted,which can provide a reference for future experiments.展开更多
In this study,we systematically investigate theαdecay preformation factors,Pα,and theαdecay half-lives of 152 nuclei around Z=82,N=126 closed shells based on the generalized liquid drop model(GLDM)with Pαbeing ext...In this study,we systematically investigate theαdecay preformation factors,Pα,and theαdecay half-lives of 152 nuclei around Z=82,N=126 closed shells based on the generalized liquid drop model(GLDM)with Pαbeing extracted from the ratio of the calculatedαdecay half-life to the experimental one.The results show that there is a remarkable linear relationship between Pαand the product of valance protons(holes)Np and valance neutrons(holes)Nn.At the same time,we extract theαdecay preformation factor values of the even–even nuclei around the Z=82,N=126 closed shells from the study of Sun et al.[J.Phys.G:Nucl.Part.Phys.,45:075106(2018)],in which theαdecay was calculated by two different microscopic formulas.We find that theαdecay preformation factors are also related to NpNn.Combining with our previous studies[Sun et al.,Phys.Rev.C,94:024338(2016);Deng et al.,ibid.96:024318(2017);Deng et al.,ibid.97:044322(2018)]and that of Seif et al.,[Phys.Rev.C,84:064608(2011)],we suspect that this phenomenon of linear relationship for the nuclei around the above closed shells is model-independent.This may be caused by the effect of the valence protons(holes)and valence neutrons(holes)around the shell closures.Finally,using the formula obtained by fitting theαdecay preformation factor data calculated by the GLDM,we calculate theαdecay half-lives of these nuclei.The calculated results agree with the experimental data well.展开更多
Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Qα value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and th...Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Qα value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the DensityDependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.展开更多
The properties of nuclei belonging to the α-decay chain of superheavy element ^295118 have been studied in the framework of axially deformed relativistic mean field （RMF） theory with the parameter set of NL-Z2 in t...The properties of nuclei belonging to the α-decay chain of superheavy element ^295118 have been studied in the framework of axially deformed relativistic mean field （RMF） theory with the parameter set of NL-Z2 in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, and α-decay energies Qα have been obtained and agree well with those from finite-range droplet model （FRDM）. The single-particle spectra of nuclei in ^295118 α-decay chain show that the shell gaps present obviously nucleon number dependence. The root-mean-square （rms） radii of proton, neutron and matter distributions change slowly from ^283112 to ^295118 but dramatically from ^279110 to ^283112, which may be due to the subshell closure at Z = 110 in ^279110. The α-decay half-lives in 295118 decay chain are evaluated by employing the cluster model and the generalized liquid drop model （GLDM）, and the overall agreement is found when they are compared with the known experimental data. The α-decay lifetimes obtained from the cluster model are slightly larger than those of GLDM ones. Finally, we predict the α-decay half-lives of Z=118, 116, 114, 112 isotopes using the cluster model and GLDM, which also indicate these two models can corroborate each other in studies on superheavy nuclei. The results from GLDM are always lower than those obtained from the cluster model.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
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 cluste...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.展开更多
Theα-particle preformation factors of nuclei above doubly magic nuclei ^(100)Sn and ^(208)Pb are investigated within the generalized liquid drop model.The results show that theα-particle preformation factors of nucl...Theα-particle preformation factors of nuclei above doubly magic nuclei ^(100)Sn and ^(208)Pb are investigated within the generalized liquid drop model.The results show that theα-particle preformation factors of nuclei near self-conjugate doubly magic ^(100)Sn are significantly larger than those of analogous nuclei just above ^(208)Pb,and they will be enhanced as the nuclei move towards the N=Z line.The proton-neutron correlation energy E_(p-n) and two protons-two neutrons correlation energy E_(2p-2n) of nuclei near ^(100)Sn also exhibit a similar situation,indicating that the interactions between protons and neutrons occupying similar single-particle orbitals could enhance theα-particle preformation factors and result in superallowed a decay.This also provides evidence of the significant role of the proton-neutron interaction onα-particle preformation.Also,the linear relationship betweenα-particle preformation factors and the product of valence protons and valence neutrons for nuclei around ^(208)Pb is broken in the100 Sn region because theα-particle preformation factor is enhanced when a nucleus near 100 Sn moves towards the N=Z line.Furthermore,the calculatedαdecay half-lives fit well with the experimental data,including the recent observed self-conjugate nuclei ^(104)Te and ^(108)Xe[Phys.Rev.Lett.121,182501(2018)].展开更多
The proton radioactivity half-lives are investigated theoretically within a hybrid method.The potential barriers preventing the emission of protons are determined in the quasimolecular shape path within a generalized ...The proton radioactivity half-lives are investigated theoretically within a hybrid method.The potential barriers preventing the emission of protons are determined in the quasimolecular shape path within a generalized liquid drop model(GLDM). The penetrability is calculated with the WentzelKramers-Brillouin(WKB) approximation. The spectroscopic factor has been taken into account in halflife calculation, which is obtained by employing the relativistic mean field(RMF) theory combined with the Bardeen-Cooper-Schrieffer(BCS) method. The half-lives within the present hybrid method reproduced the experimental data very well. Some predictions for proton radioactivity are made for future experiments.展开更多
The α particle preformation factor is extracted within a generalized liquid drop model for Z=84-92 isotopes and N=126, 128, 152, 162, 176, 184 isotones. The calculated results show clearly that the shell effects play...The α particle preformation factor is extracted within a generalized liquid drop model for Z=84-92 isotopes and N=126, 128, 152, 162, 176, 184 isotones. The calculated results show clearly that the shell effects play a key role in α particle preformation. The closer the proton and neutron numbers are to the magic numbers, the more difficult the formation of the α cluster inside the mother nucleus is. The preformation factors of the isotopes reflect that N=126 is a magic number for Po, Rn, Ra, and Th isotopes, but for U isotopes the weakening of the influence of the N=126 shell closure is evident. The trend of the factors for N=126 and N=128 isotones also support this conclusion. We extend the calculations for N=152, 162, 176, 184 isotones to explore the magic numbers for heavy and superheavy nuclei, which are probably present near Z=108 to N=152, 162 isotones and Z=116 to N=176, 184 isotones. The results also show that another subshell closure may exist after Z=124 in the superheavy nuclei. This is useful for future experiments.展开更多
In this contribution,the α preformation factors of 606 nuclei are extracted within the framework of the generalized liquid drop model(GLDM).Through the systematic analysis of the α preformation factors of even-even ...In this contribution,the α preformation factors of 606 nuclei are extracted within the framework of the generalized liquid drop model(GLDM).Through the systematic analysis of the α preformation factors of even-even Po-U isotopes,we found that there is a significant weakening of influence of N=126 shell closure in uranium,which is consistent with the results of a recent experiment [J.Khuyagbaatar et al.,Phys.Rev.Lett.115,242502(2015)],implying that N=126 may not be the magic number for U isotopes.Furthermore,we propose an improved formula with only 7 parameters to calculate α preformation factors suitable for all types of α-decay;it has fewer parameters than the original formula proposed by Zhang et al.[H.F.Zhang et al.,Phys.Rev.C 80,057301(2009)]with higher precision.The standard deviation of the α preformation factors calculated by our formula with extracted values for all 606 nuclei is 0.365 with a factor of 2.3,indicating that our improved formula can accurately reproduce the α preformation factors.Encouraged by this,the α-decay half-lives of actinide elements are predicted,which could be useful in future experiments.Notably,the predicted α-decay half-lives of two new isotopes 220 Np [Z.Y.Zhang,et al.,Phys.Rev.Lett.122,192503(2019)] and 219 Np [H.B.Yang et al.,Phys.Lett.B 777,212(2018)] are in good agreement with the experimental α-decay half-lives.展开更多
The shell correction effects on the α decay properties of heavy and superheavy nuclei have been studied in a macroscopic-microscopic manner. The macroscopic part is constructed from the generalized liquid drop model...The shell correction effects on the α decay properties of heavy and superheavy nuclei have been studied in a macroscopic-microscopic manner. The macroscopic part is constructed from the generalized liquid drop model（GLDM）, whereas the microscopic part, namely, the shell correction energy, brings about certain effects on the potential barriers and half-lives under a WKB approximation, which is emphasized in this work. The results show that the shell effects play a significant role in the estimation of the α decay half-lives within the actinide region.Predictions of the α decay half-lives are then generated for superheavy nuclei, which will provide useful information for future experiments.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos.11175074,11120101005,11105035,and 10805061the Fundamental Research Funds for the Central Universities under Grant No.lzujbky-2012-5the Knowledge Innovation Project of the Chinese Academy of Sciences under Grant No.KJCX2-EW-N01
文摘The barrier against the spontaneous fission has been determined within the Generalized Liquid Drop Model （GLDM） including the mass and charge asymmetry, and the proximity energy. The shell correction of the spherical parent nucleus is calculated by using the Strutinsky method, and the empirical shape-dependent shell correction is 6mp10yed during the deformation process. A quasi-molecular shape sequence has been defined to describe the whole process from one-body shape to two-body shape system, and a two-touching-ellipsoid is adopted when the superdeformed one-body system reaches the rupture point. On these bases the spontaneous fission barriers are systematically studied for nuclei from 2a^Th to 249 Cm for different possible exiting channels with the different mass and charge asymmetries. The double, and triple bumps are found in the fission potential energy in this region, which roughly agree with the experimental results. It is found that at around Sn-like fragment the outer fission barriers are lower, while the partner of the Sn-like fragment is in the range near l^SRu where the ground-state mass is lowered by allowing axially symmetric shapes. The preferable fission channels are distinctly pronounced, which should be corresponding to the fragment mass distributions.
基金Support by National Natural Science Foundation of China(10775061,11175054,11675066,11665019,11947229)the Fundamental Research Funds for the Central Universities(lzujbky-2017-ot04,lzujbky-2020-it01)Feitian Scholar Project of Gansu province。
文摘It is universally acknowledged that the Generalized Liquid Drop Model(GLDM)has two advantages over otherαdecay theoretical models:introduction of the quasimolecular shape mechanism and proximity energy.In the past few decades,the original proximity energy has been improved by numerous works.In the present work,the different improvements of proximity energy are examined when they are applied to the GLDM for enhancing the calculation accuracy and prediction ability ofαdecay half-lives for known and unsynthesized superheavy nuclei.The calculations ofαhalf-lives have systematic improvements in reproducing experimental data after choosing a more suitable proximity energy for application to the GLDM.Encouraged by this,theαdecay half-lives of even-even superheavy nuclei with Z=112-122 are predicted by the GLDM with a more suitable proximity energy.The predictions are consistent with calculations by the improved Royer formula and the universal decay law.In addition,the features of the predictedαdecay half-lives imply that the next double magic nucleus after ^(208)Pb is ^(298)Fl.
基金Supported by the National Natural Science Foundation of China(12175170)Hubei Provincial Natural Science Foundation of China(2023AFB035)+1 种基金Hunan Outstanding Youth Science Foundation(2022JJ10031)Natural Science Research Project of Yichang City(A23-2-028)。
文摘Cluster radioactivity is studied within the generalized liquid drop model(GLDM),in which the shell correction energy,pairing energy,and cluster preformation factor are considered.The calculations show significant improvements and can reproduce the experimental data within a factor of 8.04 after considering these physical effects.In addition,the systematic trend of the cluster preformation factors is discussed in terms of the N_(p)N_(n)scheme to study the influence of the valence proton-neutron interaction and shell effect on cluster radioactivity.It is found that log10Pcis linearly related to N_(p)N_(n).This is in agreement with a recent study[L.Qi et al.,Phys.Rev.C 108,014325(2023)],in which log10Pc,obtained using different theoretical models and treatment methods than those used in this study,also had a linear relationship with N_(p)N_(n).Combined with the work by Qi et al.,this study suggests that the linear relationship between log10Pcand N_(p)N_(n)is model-independent and both the shell effect and valence proton-neutron interaction play essential roles in cluster radioactivity.An analytical formula is proposed to calculate the cluster preformation factor based on the N_(p)N_(n)scheme.In addition,the cluster preformation factors and the cluster radioactivity half-lives of some heavy nuclei are predicted,which can provide a reference for future experiments.
基金Supported in part by the National Natural Science Foundation of China(11205083,11505100,11705055)the Construct Program of the Key Discipline in Hunan Province,the Research Foundation of Education Bureau of Hunan Province,China(15A159,18A237)+4 种基金the Natural Science Foundation of Hunan Province,China(2015JJ3103,2015JJ2121,2018JJ3324)the Innovation Group of Nuclear and Particle Physics in USC,the Shandong Province Natural Science Foundation,China(ZR2015AQ007)the Hunan Provincial Innovation Foundation For Postgraduate(CX20190714,CX20200909)the National Innovation Training Foundation of China(201910555161)and the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(2019KFZ10)。
文摘In this study,we systematically investigate theαdecay preformation factors,Pα,and theαdecay half-lives of 152 nuclei around Z=82,N=126 closed shells based on the generalized liquid drop model(GLDM)with Pαbeing extracted from the ratio of the calculatedαdecay half-life to the experimental one.The results show that there is a remarkable linear relationship between Pαand the product of valance protons(holes)Np and valance neutrons(holes)Nn.At the same time,we extract theαdecay preformation factor values of the even–even nuclei around the Z=82,N=126 closed shells from the study of Sun et al.[J.Phys.G:Nucl.Part.Phys.,45:075106(2018)],in which theαdecay was calculated by two different microscopic formulas.We find that theαdecay preformation factors are also related to NpNn.Combining with our previous studies[Sun et al.,Phys.Rev.C,94:024338(2016);Deng et al.,ibid.96:024318(2017);Deng et al.,ibid.97:044322(2018)]and that of Seif et al.,[Phys.Rev.C,84:064608(2011)],we suspect that this phenomenon of linear relationship for the nuclei around the above closed shells is model-independent.This may be caused by the effect of the valence protons(holes)and valence neutrons(holes)around the shell closures.Finally,using the formula obtained by fitting theαdecay preformation factor data calculated by the GLDM,we calculate theαdecay half-lives of these nuclei.The calculated results agree with the experimental data well.
基金Supported by Natural Science Foundation of China (10775061, 10505016, 10575119)
文摘Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Qα value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the DensityDependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.
基金Supported by the Natural Science Foundation of China under Grant Nos.10775061,10505016,10575119,and 10805016the CAS Knowledge Innovation Project under Grant No.KJCX-SYW-N02the Major State Basic Research Developing Program of China under Grant No.2007CB815004
文摘The properties of nuclei belonging to the α-decay chain of superheavy element ^295118 have been studied in the framework of axially deformed relativistic mean field （RMF） theory with the parameter set of NL-Z2 in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, and α-decay energies Qα have been obtained and agree well with those from finite-range droplet model （FRDM）. The single-particle spectra of nuclei in ^295118 α-decay chain show that the shell gaps present obviously nucleon number dependence. The root-mean-square （rms） radii of proton, neutron and matter distributions change slowly from ^283112 to ^295118 but dramatically from ^279110 to ^283112, which may be due to the subshell closure at Z = 110 in ^279110. The α-decay half-lives in 295118 decay chain are evaluated by employing the cluster model and the generalized liquid drop model （GLDM）, and the overall agreement is found when they are compared with the known experimental data. The α-decay lifetimes obtained from the cluster model are slightly larger than those of GLDM ones. Finally, we predict the α-decay half-lives of Z=118, 116, 114, 112 isotopes using the cluster model and GLDM, which also indicate these two models can corroborate each other in studies on superheavy nuclei. The results from GLDM are always lower than those obtained from the cluster model.
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.
基金Supported by National Natural Science Foundation of China (10775061, 10505016, 10575119)Fundamental Research Fund for Physics and Mathematics of Lanzhou University (LZULL200805)+1 种基金CAS Knowledge Innovation Project (KJCX-SYW-N02)Major State Basic Research Developing Program of China (2007CB815004)
文摘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.
基金Supported by the National Natural Science Foundation of China(12175170,11675066,12005303)。
文摘Theα-particle preformation factors of nuclei above doubly magic nuclei ^(100)Sn and ^(208)Pb are investigated within the generalized liquid drop model.The results show that theα-particle preformation factors of nuclei near self-conjugate doubly magic ^(100)Sn are significantly larger than those of analogous nuclei just above ^(208)Pb,and they will be enhanced as the nuclei move towards the N=Z line.The proton-neutron correlation energy E_(p-n) and two protons-two neutrons correlation energy E_(2p-2n) of nuclei near ^(100)Sn also exhibit a similar situation,indicating that the interactions between protons and neutrons occupying similar single-particle orbitals could enhance theα-particle preformation factors and result in superallowed a decay.This also provides evidence of the significant role of the proton-neutron interaction onα-particle preformation.Also,the linear relationship betweenα-particle preformation factors and the product of valence protons and valence neutrons for nuclei around ^(208)Pb is broken in the100 Sn region because theα-particle preformation factor is enhanced when a nucleus near 100 Sn moves towards the N=Z line.Furthermore,the calculatedαdecay half-lives fit well with the experimental data,including the recent observed self-conjugate nuclei ^(104)Te and ^(108)Xe[Phys.Rev.Lett.121,182501(2018)].
基金National Natural Science Foundation of China(11175074,11475050,11265013)Knowledge Innovation Project of Chinese Academy of Sciences(KJCX2-EW-N02)
文摘The proton radioactivity half-lives are investigated theoretically within a hybrid method.The potential barriers preventing the emission of protons are determined in the quasimolecular shape path within a generalized liquid drop model(GLDM). The penetrability is calculated with the WentzelKramers-Brillouin(WKB) approximation. The spectroscopic factor has been taken into account in halflife calculation, which is obtained by employing the relativistic mean field(RMF) theory combined with the Bardeen-Cooper-Schrieffer(BCS) method. The half-lives within the present hybrid method reproduced the experimental data very well. Some predictions for proton radioactivity are made for future experiments.
基金Supported by National Natural Science Foundation of China(11675066,11475050)Fundamental Research Funds for the Central Universities(lzujbky-2017-ot04)Feitian Scholar Project of Gansu Province
文摘The α particle preformation factor is extracted within a generalized liquid drop model for Z=84-92 isotopes and N=126, 128, 152, 162, 176, 184 isotones. The calculated results show clearly that the shell effects play a key role in α particle preformation. The closer the proton and neutron numbers are to the magic numbers, the more difficult the formation of the α cluster inside the mother nucleus is. The preformation factors of the isotopes reflect that N=126 is a magic number for Po, Rn, Ra, and Th isotopes, but for U isotopes the weakening of the influence of the N=126 shell closure is evident. The trend of the factors for N=126 and N=128 isotones also support this conclusion. We extend the calculations for N=152, 162, 176, 184 isotones to explore the magic numbers for heavy and superheavy nuclei, which are probably present near Z=108 to N=152, 162 isotones and Z=116 to N=176, 184 isotones. The results also show that another subshell closure may exist after Z=124 in the superheavy nuclei. This is useful for future experiments.
基金Supported by the National Natural Science Foundation of China (11675066, 11665019, 11947229)Fundamental Research Funds for the Central Universities(lzujbky-2017-ot04)Feitian Scholar Project of Gansu province。
文摘In this contribution,the α preformation factors of 606 nuclei are extracted within the framework of the generalized liquid drop model(GLDM).Through the systematic analysis of the α preformation factors of even-even Po-U isotopes,we found that there is a significant weakening of influence of N=126 shell closure in uranium,which is consistent with the results of a recent experiment [J.Khuyagbaatar et al.,Phys.Rev.Lett.115,242502(2015)],implying that N=126 may not be the magic number for U isotopes.Furthermore,we propose an improved formula with only 7 parameters to calculate α preformation factors suitable for all types of α-decay;it has fewer parameters than the original formula proposed by Zhang et al.[H.F.Zhang et al.,Phys.Rev.C 80,057301(2009)]with higher precision.The standard deviation of the α preformation factors calculated by our formula with extracted values for all 606 nuclei is 0.365 with a factor of 2.3,indicating that our improved formula can accurately reproduce the α preformation factors.Encouraged by this,the α-decay half-lives of actinide elements are predicted,which could be useful in future experiments.Notably,the predicted α-decay half-lives of two new isotopes 220 Np [Z.Y.Zhang,et al.,Phys.Rev.Lett.122,192503(2019)] and 219 Np [H.B.Yang et al.,Phys.Lett.B 777,212(2018)] are in good agreement with the experimental α-decay half-lives.
基金Supported by National Natural Science Foundation of China(11675066,11475050)the Fundamental Research Funds for the Central Universities(lzujbky-2017-ot04)Feitian Scholar Project of Gansu Province
文摘The shell correction effects on the α decay properties of heavy and superheavy nuclei have been studied in a macroscopic-microscopic manner. The macroscopic part is constructed from the generalized liquid drop model（GLDM）, whereas the microscopic part, namely, the shell correction energy, brings about certain effects on the potential barriers and half-lives under a WKB approximation, which is emphasized in this work. The results show that the shell effects play a significant role in the estimation of the α decay half-lives within the actinide region.Predictions of the α decay half-lives are then generated for superheavy nuclei, which will provide useful information for future experiments.
