Nuclearβ-decay,a typical decay process for unstable nuclei,is a key mechanism for producing heavy elements in the Universe.In this study,neural networks were employed to predictβ-decay half-lives and,for the first t...Nuclearβ-decay,a typical decay process for unstable nuclei,is a key mechanism for producing heavy elements in the Universe.In this study,neural networks were employed to predictβ-decay half-lives and,for the first time,to identify abnormal trends in nuclearβ-decay half-lives based on deviations between experimental values and the predictions of neural networks.Nuclei exhibiting anomalous increases,abrupt peaks,sharp decreases,abnormal odd-even oscillations,and excessively large experimental errors in theirβ-decay half-lives,which deviate from systematic patterns,were identified through deviations.These anomalous phenomena may be associated with shell effects,shape coexistence,or discrepancies in the experimental data.The discovery and analysis of these abnormal nuclei provide a valuable reference for further investigations using sophisticated microscopic theories,potentially offering insights into new physics through studies of nuclearβ-decay half-lives.展开更多
We generalize the formula of β^+-decay half-lives [Phys.Rev.C 78 (2006) 014305] to include all availabledata of nuclei far from the β-stable line. Good agreement with experimental data is obtained by taking into acc...We generalize the formula of β^+-decay half-lives [Phys.Rev.C 78 (2006) 014305] to include all availabledata of nuclei far from the β-stable line. Good agreement with experimental data is obtained by taking into accountthe even-odd (e-o) effect.It is shown that the e-o effect on β^+-deeay half-life is apparent for the allowed β^+-transition,whereas it is not apparent for the first and second forbidden transitions.This demonstrates that the allowed β^+-transitionis more sensitive to the nuclear even-odd effect than the forbidden β^+-transition.The underlying physics is discussed.This formula can be used to predict the β^+-decay half-lives of the nuclei far from β-stability.It is useful to experimentalphysicists for analyzing the data of β^+-decay.展开更多
The experimental values of 2059 β-decay half-lives are systematically analyzed and investigated. We have found that they are in satisfactory agreement with Benford＇s law, which states that the frequency of occurrenc...The experimental values of 2059 β-decay half-lives are systematically analyzed and investigated. We have found that they are in satisfactory agreement with Benford＇s law, which states that the frequency of occurrence of each figure, 1-9, as the first significant digit in a surprisingly large number of different data sets follows a logarithmic distribution favoring the smaller ones. Benford＇s logarithmic distribution of β-deeay half-lives can be explained in terms of Neweomb＇s justification of Benford＇s law and empirical exponential law of β-decay half-lives. Moreover, we test the calculated values of 6721 β-decay half-lives with the aid of Benford＇s law. This indicates that Benford＇s law is useful for theoretical physicists to test their methods for calculating β-decay half-lives.展开更多
We have systematically analyzed the experimental β--decay half-lives of waiting point heavy nuclei around neutron number N = 126. A new set of parameters for the exponential formula of β^--decay half-lives is propos...We have systematically analyzed the experimental β--decay half-lives of waiting point heavy nuclei around neutron number N = 126. A new set of parameters for the exponential formula of β^--decay half-lives is proposed. The forbidden transition effects are included in the new set of parameters self-consistently. Theoretical β^--decay half-lives of nuclei around N = 126 are compared with recent theoretical results and experimental data. It is found that the new theoretical results are in better agreement with experimental data. The unknown β^--decay half-lives of some nuclei in this region are predicted for studies on nuclear structure far from stability and the nucleosynthesis in stars.展开更多
A new version of the generalized density-dependent cluster model （GDDCM） is developed to describe an α particle tunneling through a deformed potential barrier. The microscopic deformed potential is numerically cons...A new version of the generalized density-dependent cluster model （GDDCM） is developed to describe an α particle tunneling through a deformed potential barrier. The microscopic deformed potential is numerically constructed in the double-folding model using the multipole ex- pansion method. The decay width of an α-cluster state is evaluated using the integral of the quasi-bound state wave function, the scattering state wave function, and the difference of poten- tials. We perform a systematic calculation of α-decay half-lives for favored transitions in even-even nuclei ranging from Z=52 to Z=104. The calculated half-lives are in good agreement with the experimental values. The relation between nuclear deformations and α-decay half-lives is also discussed in details.展开更多
α decay half-lives are calculated using the Qα values obtained by Semi-empirical Shell Model in the framework of the Unified Fission Model （UFM） with the Coulomb repulsion, nuclear attraction due to proximity pote...α decay half-lives are calculated using the Qα values obtained by Semi-empirical Shell Model in the framework of the Unified Fission Model （UFM） with the Coulomb repulsion, nuclear attraction due to proximity potential, and rotational energy due to angular momentum transfer of a particle. In addition, the calculated and experimental half-lives of 425 nuclei are compared to check the validity of the model applied on α decay. The calculated half-lives of decay are in good agreement with the experimental data. Finally, some useful predications on the α decay half-lives are provided for future experiments.展开更多
Nuclear double β--decay with two neutrinos is an important decay mode for some unstable nuclei. Based on the available experimental data of nuclear double β--decay, we propose that there is a law between the logarit...Nuclear double β--decay with two neutrinos is an important decay mode for some unstable nuclei. Based on the available experimental data of nuclear double β--decay, we propose that there is a law between the logarithm of double β--decay half-lives and the reciprocal of the decay energy. The physics behind the law is discussed and it is found that this is associated with the universal properties of the weak interaction. This doubleβ--decay law is similar to the famous Geiger-Nuttall law of α-decay. The law is applied to predictions of the nuclear double β--decay half-lives for six even-even nuclei from Z = 84 to Z = 98 and we found that232 Th is very interesting for future experiments. The branching ratios between double β--decay and α-decay are also estimated for the six even-even nuclei and this is useful for future experimental search of new emitters of doubleβ--decay.展开更多
In the present work,based on a Gamow-like model,considering the deformation effect of Coulomb potential,where the effective nuclear radius constant is parameterized,we systematically investigate the cluster radioactiv...In the present work,based on a Gamow-like model,considering the deformation effect of Coulomb potential,where the effective nuclear radius constant is parameterized,we systematically investigate the cluster radioactivity half-lives of 25 trans-lead nuclei.For comparison,a universal decay law(UDL)proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a new semi-empirical formula for exotic cluster decay proposed by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and a scaling law proposed by Horoi[J.Phys.G:Nucl.Part.Phys.30,945(2004)]are also used.The calculated results within the deformed Gamow-like model are in better agreement with the experimental half-lives.The deformation effect is also discussed within both the Gamow-like and deforemed Gamow-like models.Moreover,we extend this model to predict the cluster radioactivity half-lives of 49 nuclei whose decay energies are energetically allowed or observed but not yet quantified in NUBASE2020.展开更多
An empirical formula of nuclearβ-decay half-lives is proposed by including the transition-strength contribution.The inclusion of the transition-strength contribution can reduce nuclearβ-decay half-lives by about an ...An empirical formula of nuclearβ-decay half-lives is proposed by including the transition-strength contribution.The inclusion of the transition-strength contribution can reduce nuclearβ-decay half-lives by about an order of magnitude,and its effect gradually increases toward the neutron-rich or heavy nuclear regions.For nuclearβ-decay half-lives less than 1 s,the empirical formula can describe the experimental data within approximately2 times,which is more accurate than the sophisticated microscopic models.The transition-strength contribution can also be effectively considered by refitting the parameters of other empirical formulas without the transition-strength term although they will still significantly deviate from the new empirical formula in light or heavy neutron-rich nuclear regions.This indicates that the inclusion of the transition-strength contribution in the empirical formula is crucial for the global description of nuclearβ-decay half-lives.The extrapolation ability of the new empirical formula was verified by the newly measuredβ-decay half-lives.展开更多
In this study,proton emission half-lives were investigated for deformed proton emitters with 53≤Z≤83based on the presented deformed Gamow-like model,where the deformation effect was included in the Coulomb potential...In this study,proton emission half-lives were investigated for deformed proton emitters with 53≤Z≤83based on the presented deformed Gamow-like model,where the deformation effect was included in the Coulomb potential.The experimental half-lives of proton emitters can be reproduced within a factor of 3.45.For comparison,the results from the universal decay law and the new Geiger-Nuttall law are also presented.Furthermore,the relevance of the half-lives to the angular momentum l for ^(117)La,^(121)Pr,^(135)Tb,and ^(141)Ho were analyzed,and the corresponding possible values of l were proposed:l=3,3,4,4.展开更多
In this paper,using theαparticle preformation probabilities Pαfrom Xu et al.[Xu and Ren,Nucl.Phys.A 760,303(2005)],which were extracted by fitting experimental half-lives ofαdecay,based on a phenomenological harmon...In this paper,using theαparticle preformation probabilities Pαfrom Xu et al.[Xu and Ren,Nucl.Phys.A 760,303(2005)],which were extracted by fitting experimental half-lives ofαdecay,based on a phenomenological harmonic oscillator potential model(HOPM)[Bayrak,J Phys G 47,025102(2020)],refitting 178αdecay half-lives of even-even nuclei obtained from the latest nuclear property table NUBASE2020,we obtain the only one adjustable parameter V0-162.6 MeV in the HOPM,i.e.,the depth of nuclear potential.The corresponding root-mean-square(rms)deviation isσ-0.322.Furthermore,to consider the contribution of centrifugal potential to unfavoredαdecay half-lives,adding a new term■(d and l are the adjustable parameter and orbital angular momentum carried away by emittedαparticle)to the logarithmic form of favoredαdecay half-lives under the HOPM framework,we propose an improved simple model(ISM)for calculating favored and unfavoredαdecay half-lives.Fitting the experimental half-lives of 205 unfavoredαdecay,we obtain d-0.381.The ISM is used to calculate the unfavoredαdecay half-lives of 128 odd-A and 77 odd-odd nuclei.The results improve by 54.2%and 53.6%,respectively,compared with HOPM.In addition,we extend the ISM to predict theαdecay half-lives of 144 nuclei with Z=117,118,119,and 120.For comparison,the improved model with eight parameters(DUR)proposed by Deng et al.[Deng,Phys.Rev.C 101,034307(2020)]and the modified universal decay law(MUDL)proposed by Soylu et al.[Soylu,Nucl.Phys.A 1013,122221(2021)]are also used.The predictions of these models and/or formulas are generally consistent with each other.展开更多
The α-decay properties of well-deformed even-even nuclei are systematically calculated within the multichannel cluster model (MCCM). Instead of working in the WKB framework, the quasibound solution to the coupled Sch...The α-decay properties of well-deformed even-even nuclei are systematically calculated within the multichannel cluster model (MCCM). Instead of working in the WKB framework, the quasibound solution to the coupled Schro¨dinger equation is presented with outgoing wave boundary conditions, and the coupling potential is taken into full account in terms of the general quantum theories. The calculated α-decay half-lives are found to agree well with the experimental data with a mean factor of less than 2. The fine structure observed in α decay is also well reproduced by the four-channel microscopic calculation. Very strikingly, the MCCM can give relatively precise descriptions of the branching ratio to excited 4+ states, which is often overestimated in the usual WKB calculations. We expect it to be a significant development of theoretical models toward quantitative descriptions of α transitions to high-spin daughter states.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
Experimental data ofβ--decay half-lives of nuclei with atomic number between 20 and 190 are investigated.A systematic formula has been proposed to calculateβ^--decay half-lives of neutron-rich nuclei,with a particul...Experimental data ofβ--decay half-lives of nuclei with atomic number between 20 and 190 are investigated.A systematic formula has been proposed to calculateβ^--decay half-lives of neutron-rich nuclei,with a particular consideration on shell and pair effects,the decay energy Q as well as the nucleon numbers(Z,N).Although the formula has relatively few parameters,it reproduces the experimentalβ^--decay half-lives of neutron-rich nuclei very well.The predicted half-lives for the r-process relevant nuclei obtained with the current formula serve as reliable input in the r-process model calculations.展开更多
We investigate the half-lives of β + /EC(electron capture) decay using the proton-neutron quasiparticle random-phase approximation(pnQRPA) with a δ-form Gamow-Teller residual interaction.Both particle-hole and parti...We investigate the half-lives of β + /EC(electron capture) decay using the proton-neutron quasiparticle random-phase approximation(pnQRPA) with a δ-form Gamow-Teller residual interaction.Both particle-hole and particle-particle residual interactions are consistently introduced in dealing with the pnQRPA matrix equation.The sensitivity of the calculated half-lives to some physical quantities used in the calculations is examined.Calculations are performed for even-even neutron-deficient isotopes ranging from Z = 10 to Z = 76.Good agreement between experiment and theory is achieved especially for the nuclei far from stability,and the results of our calculations are discussed with comparison with other theoretical results.Predictions on the β-decay half-lives of some very neutron-deficient nuclei are also given for reference in future experiments.展开更多
In this study,considering the modified preformation probability P_(c)to be log_(10)P_(c)=(A_(c)−1)/3log_(10)P_(α)+c′,where P_(α)and c′are theα-particle preformation probability and an adjustable parameter propose...In this study,considering the modified preformation probability P_(c)to be log_(10)P_(c)=(A_(c)−1)/3log_(10)P_(α)+c′,where P_(α)and c′are theα-particle preformation probability and an adjustable parameter proposed by Wang et al.[Chin.Phys.C 45,044111(2021)],respectively,we extend a new simple model put forward by Bayrak[J.Phys.G 47,025102(2020)]to systematically study the cluster radioactivity half-lives of 28 trans-lead nuclei ranging from^(222)Fr to^(242)Cm,which is based on the Wentzel-Kramers-Brillouin approximation and Bohr–Sommerfeld quantization condition.For comparison,a universal decay law proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a three-parameter model-independent formula put forward by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and the semi-empirical model proposed by Tavares et al.[Eur.Phys.J.A 49,1(2013)]are used.Our calculated results reproduce the experimental data well,with a standard deviation of 0.818.Furthermore,we use this model to predict the cluster radioactivity half-lives of 51 possible cluster radioactive candidates whose cluster radioactivities are energetically allowed or observed but not yet quantified in NUBASE2020.展开更多
In this study,derived from Balasubramaniam’s formula[Phys.Rev.C 70,017301(2004)]and further considering the effect of the parent nucleus mass,blocking effect,and effect of reduced mass on cluster radioactivity half-l...In this study,derived from Balasubramaniam’s formula[Phys.Rev.C 70,017301(2004)]and further considering the effect of the parent nucleus mass,blocking effect,and effect of reduced mass on cluster radioactivity half-lives,we propose a new Geiger-Nuttall law that is model-independent to systematically evaluate the halflives of this process for 16 even-even nuclei and 10 odd-A nuclei.For comparison,a single universal curve for cluster radioactivity andαdecay proposed by Poenaru[Phys.Rev.C 83,014601(2011)],a scaling law proposed by Horoi[J.Phys.G:Nucl.Part.Phys.30,945(2004)],an extension of the Viola-Seaborg formula fromαdecay to cluster radioactivity proposed by Ren et al.[Phys.Rev.C 70,034304(2004)],a new semi-empirical formula for exotic cluster decay proposed by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and a unified formula for the half-lives ofαdecay and cluster radioactivity proposed by Ni et al.[Phys.Rev.C 78,044310(2008)]are also used.The calculated results of our new Geiger-Nuttall law are in good agreement with the experimental half-lives,with the least rms being 0.606,and are better than the compared values.Moreover,we extend this formula to predict the cluster radioactivity half-lives of 51 nuclei whose decay energies are energetically allowed or observed but not yet quantified in NUBASE2020.展开更多
In this study,based on Wentzel-Kramers-Brillouin theory,we systematically investigate the cluster radioactivity half-lives of 22 nuclei ranging from^(221)Fr to^(242)Cm using a phenomenological model that considers the...In this study,based on Wentzel-Kramers-Brillouin theory,we systematically investigate the cluster radioactivity half-lives of 22 nuclei ranging from^(221)Fr to^(242)Cm using a phenomenological model that considers the screened electrostatic effect of the Coulomb potential.In this model,there are two adjustable parameters,t and g,which are related to the screened electrostatic barrier and the strength of the spectroscopic factor,respectively.The calculated results indicate that this model can effectively reproduce the experimental data,with a corresponding rootmean-square deviation of 0.660.In addition,we extend this model to predict the half-lives of possible cluster radioactive candidates whose cluster radioactivities are energetically allowed or observed but not yet quantified in the evaluated nuclear properties table NUBASE2020.The predicted results are consistent with those obtained using other theoretical models and/or empirical formulas,including the universal decay law proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a semi-empirical model for bothαdecay and cluster radioactivity proposed by Santhosh et al.[J.Phys.G 35,085102(2008)],and a unified formula for the half-lives ofαdecay and cluster radioactivity proposed by Ni et al.[Phys.Rev.C 78,044310(2008)].展开更多
In the present work,based on the Wentzel-Kramers-Brillouin(WKB)theory,considering the cluster preformation probability(Pc),we systematically investigate the cluster radioactivity half-lives of 22 trans-lead nuclei ran...In the present work,based on the Wentzel-Kramers-Brillouin(WKB)theory,considering the cluster preformation probability(Pc),we systematically investigate the cluster radioactivity half-lives of 22 trans-lead nuclei ranging from221Fr to242Cm.When the mass number of the emitted cluster Ac<28,Pcis obtained by the exponential relationship of Pcto theαdecay preformation probability(Pα)proposed by R.Blendowskeis et al.[Phys.Rev.Lett.61,1930(1988)],while Pαis calculated through the cluster-formation model(CFM).When Ac≥28,Pcis calculated through the charge-number dependence of Pcon the decay products proposed by Ren et al.[Phys.Rev.C70,034304(2004)].The half-lives of cluster radioactivity have been calculated by the density-dependent cluster model[Phys.Rev.C 70,034304(2004)]and by the unified formula of half-lives for alpha decay and cluster radioactivity[Phys.Rev.C 78,044310(2008)].For comparison,a universal decay law(UDL)proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a semi-empirical model for bothαdecay and cluster radioactivity proposed by Santhosh[J.Phys.G:Nucl.Part.Phys.35,085102(2008)],and a unified formula of half-lives for alpha decay and cluster radioactivity[Phys.Rev.C 78,044310(2008)]are also used.The calculated results of our work,Ni’s formula,and the UDL can well reproduce the experimental data and are better than those of Santhosh’s model.In addition,we extend this model to predict the half-lives for 51 nuclei,whose cluster radioactivity is energetically allowed or observed but not yet quantified in NUBASE2020.展开更多
Nuclear double β^--decays with two neutrinos were observed for many years and a systematic law describing the relation between their half-lives and decay energies was also proposed recently [Phys Rev C, 2014, 89： 06...Nuclear double β^--decays with two neutrinos were observed for many years and a systematic law describing the relation between their half-lives and decay energies was also proposed recently [Phys Rev C, 2014, 89： 064603]. However, double β^＋ -decay （β^＋β^＋） with emission of both two positrons and two neutrinos has not been observed up to date. In this article, we pcrform a systematic analysis on the candidates of double β^＋-decay, based on the 2012 nuclear mass table. Eight nuclei are found to be the good candidates for double β^＋-decay and their half-lives are predicted according to the generalization of the systematic law to double β^＋-decay. As far as we know, there is no theoretical result on double β^＋-decay of nucleus ^154Dy and our result is the first prediction on this nucleus. This is also the first complete research on eight double β^＋-decay candidates based on the available data of nuclear masses. It is expected that the calculated half-lives of double β^＋-decay in this article will be useful for future experimental search of double β^＋-decay.展开更多
基金supported by the‘Young Scientist Scheme’of the National Key R&D Program of China(No.2021YFA1601500)National Natural Science Foundation of China(Nos.12075104,12375109,11875070,and 11935001)+1 种基金Anhui Project(Z010118169)Key Research Foundation of the Education Ministry of Anhui Province(No.2023AH050095)。
文摘Nuclearβ-decay,a typical decay process for unstable nuclei,is a key mechanism for producing heavy elements in the Universe.In this study,neural networks were employed to predictβ-decay half-lives and,for the first time,to identify abnormal trends in nuclearβ-decay half-lives based on deviations between experimental values and the predictions of neural networks.Nuclei exhibiting anomalous increases,abrupt peaks,sharp decreases,abnormal odd-even oscillations,and excessively large experimental errors in theirβ-decay half-lives,which deviate from systematic patterns,were identified through deviations.These anomalous phenomena may be associated with shell effects,shape coexistence,or discrepancies in the experimental data.The discovery and analysis of these abnormal nuclei provide a valuable reference for further investigations using sophisticated microscopic theories,potentially offering insights into new physics through studies of nuclearβ-decay half-lives.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10535010 and 10775068Major State Basic Research Developing Program under Grant No. 2007CB815004+1 种基金the CAS Knowledge Innovation Project under Grant No. KJCX2-SW-N02the Research Fund of High Education under Grant No. 20010284036
文摘We generalize the formula of β^+-decay half-lives [Phys.Rev.C 78 (2006) 014305] to include all availabledata of nuclei far from the β-stable line. Good agreement with experimental data is obtained by taking into accountthe even-odd (e-o) effect.It is shown that the e-o effect on β^+-deeay half-life is apparent for the allowed β^+-transition,whereas it is not apparent for the first and second forbidden transitions.This demonstrates that the allowed β^+-transitionis more sensitive to the nuclear even-odd effect than the forbidden β^+-transition.The underlying physics is discussed.This formula can be used to predict the β^+-decay half-lives of the nuclei far from β-stability.It is useful to experimentalphysicists for analyzing the data of β^+-decay.
基金supported by the National Natural Science Foundation of China under Grant Nos. 10675090, 10535010, and 10775068the National Fund for Forstering Talents of Basic Science under Grant No. J0630316+2 种基金the 973 State Key Basic Research and Development Program of China under Grant No. 2007CB815004the CAS Knowledge Innovation Project under Grant No. KJCX2-SW-N02the Research Fund of Doctoral Points under Grant No. 20070284016
文摘The experimental values of 2059 β-decay half-lives are systematically analyzed and investigated. We have found that they are in satisfactory agreement with Benford＇s law, which states that the frequency of occurrence of each figure, 1-9, as the first significant digit in a surprisingly large number of different data sets follows a logarithmic distribution favoring the smaller ones. Benford＇s logarithmic distribution of β-deeay half-lives can be explained in terms of Neweomb＇s justification of Benford＇s law and empirical exponential law of β-decay half-lives. Moreover, we test the calculated values of 6721 β-decay half-lives with the aid of Benford＇s law. This indicates that Benford＇s law is useful for theoretical physicists to test their methods for calculating β-decay half-lives.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11565010,U1731238,11365006,11761161001Guizhou Province Science and Technology Innovation Talent Team under Grant No.2015(4015)+4 种基金The Innovation Team Foundation of the Education Department of Guizhou Province under Grant No.2014-35the Training Program for Excellent Young Talents in Science and Technology of Guizhou Province under Grant No.2011-29the Scientific Research Program for the Returned Overseas Chinese Scholars of Guizhou Province,under Grant No.2013-03the Science and Technology Development Fund(FDCT) of Macao under Grant Nos.020/2014/A1,008/2017/AFJ,119/2017/A3the Key Program of the Student Scientific Research Foundation for Natural Science of Guizhou Normal University
文摘We have systematically analyzed the experimental β--decay half-lives of waiting point heavy nuclei around neutron number N = 126. A new set of parameters for the exponential formula of β^--decay half-lives is proposed. The forbidden transition effects are included in the new set of parameters self-consistently. Theoretical β^--decay half-lives of nuclei around N = 126 are compared with recent theoretical results and experimental data. It is found that the new theoretical results are in better agreement with experimental data. The unknown β^--decay half-lives of some nuclei in this region are predicted for studies on nuclear structure far from stability and the nucleosynthesis in stars.
基金supported by National Natural Science Foundation of China(Nos.10535010,10675090,10775068,10735010,10975072,11035001)973 National Major State Basic Research and Development of China(Nos.2007CB815004,2010CB327803)+1 种基金CAS Knowledge Innovation Project(No.KJCX2-SW-N02)Research Fund of Doctoral Point(RFDP) of China(Nos.20070284016,20100091110028)
文摘A new version of the generalized density-dependent cluster model （GDDCM） is developed to describe an α particle tunneling through a deformed potential barrier. The microscopic deformed potential is numerically constructed in the double-folding model using the multipole ex- pansion method. The decay width of an α-cluster state is evaluated using the integral of the quasi-bound state wave function, the scattering state wave function, and the difference of poten- tials. We perform a systematic calculation of α-decay half-lives for favored transitions in even-even nuclei ranging from Z=52 to Z=104. The calculated half-lives are in good agreement with the experimental values. The relation between nuclear deformations and α-decay half-lives is also discussed in details.
基金Supported by the Natural Science Foundation of China under Grant Nos.10775061,10875152,10875151,and 10975064the Fundamental Research Fund for Physics and Mathematic of Lanzhou University(LZULL200805)+2 种基金the Fundamental Research Funds for the Central Universities(lzujbky-2009-21)the Knowledge Innovation Project of the Chinese Academy of Sciences under Grant Nos.KJCX2-SW-N17,KJCX3-SW-N02Major State Basic Research Development Program under Grant No.2007CB815000
文摘α decay half-lives are calculated using the Qα values obtained by Semi-empirical Shell Model in the framework of the Unified Fission Model （UFM） with the Coulomb repulsion, nuclear attraction due to proximity potential, and rotational energy due to angular momentum transfer of a particle. In addition, the calculated and experimental half-lives of 425 nuclei are compared to check the validity of the model applied on α decay. The calculated half-lives of decay are in good agreement with the experimental data. Finally, some useful predications on the α decay half-lives are provided for future experiments.
基金Supported by the National Natural Science Foundation of China(Nos.11035001,10975072,11120101005 and 11375086)the Research Fund of Doctoral Point(RFDP)(No.20070284016)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Nuclear double β--decay with two neutrinos is an important decay mode for some unstable nuclei. Based on the available experimental data of nuclear double β--decay, we propose that there is a law between the logarithm of double β--decay half-lives and the reciprocal of the decay energy. The physics behind the law is discussed and it is found that this is associated with the universal properties of the weak interaction. This doubleβ--decay law is similar to the famous Geiger-Nuttall law of α-decay. The law is applied to predictions of the nuclear double β--decay half-lives for six even-even nuclei from Z = 84 to Z = 98 and we found that232 Th is very interesting for future experiments. The branching ratios between double β--decay and α-decay are also estimated for the six even-even nuclei and this is useful for future experimental search of new emitters of doubleβ--decay.
基金Supported in part by the National Natural Science Foundation of China(12175100,11975132)the construct program of the key discipline in hunan province,the Research Foundation of Education Bureau of Hunan Province,China(18A237)+2 种基金the Shandong Province Natural Science Foundation,China(ZR2022JQ04)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(2019KFZ10)the Innovation Group of Nuclear and Particle Physics in USC,Hunan Provincial Innovation Foundation for Postgraduate(CX20210942)。
文摘In the present work,based on a Gamow-like model,considering the deformation effect of Coulomb potential,where the effective nuclear radius constant is parameterized,we systematically investigate the cluster radioactivity half-lives of 25 trans-lead nuclei.For comparison,a universal decay law(UDL)proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a new semi-empirical formula for exotic cluster decay proposed by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and a scaling law proposed by Horoi[J.Phys.G:Nucl.Part.Phys.30,945(2004)]are also used.The calculated results within the deformed Gamow-like model are in better agreement with the experimental half-lives.The deformation effect is also discussed within both the Gamow-like and deforemed Gamow-like models.Moreover,we extend this model to predict the cluster radioactivity half-lives of 49 nuclei whose decay energies are energetically allowed or observed but not yet quantified in NUBASE2020.
基金supported by the National Natural Science Foundation of China(12375109,11875070,11935001)the Anhui Project(Z010118169)the Key Research Foundation of Education Ministry of Anhui Province,China(2023AH050095)。
文摘An empirical formula of nuclearβ-decay half-lives is proposed by including the transition-strength contribution.The inclusion of the transition-strength contribution can reduce nuclearβ-decay half-lives by about an order of magnitude,and its effect gradually increases toward the neutron-rich or heavy nuclear regions.For nuclearβ-decay half-lives less than 1 s,the empirical formula can describe the experimental data within approximately2 times,which is more accurate than the sophisticated microscopic models.The transition-strength contribution can also be effectively considered by refitting the parameters of other empirical formulas without the transition-strength term although they will still significantly deviate from the new empirical formula in light or heavy neutron-rich nuclear regions.This indicates that the inclusion of the transition-strength contribution in the empirical formula is crucial for the global description of nuclearβ-decay half-lives.The extrapolation ability of the new empirical formula was verified by the newly measuredβ-decay half-lives.
基金Supported in part by the National Natural Science Foundation of China (12175100, 11975132)the Construct Program of the Key Discipline in Hunan Province+5 种基金the Research Foundation of Education Bureau of Hunan Province,China (21B0402, 18A237)the Natural Science Foundation of Hunan Province,China (2018JJ2321)the Innovation Group of Nuclear and Particle Physics in USCthe Shandong Province Natural Science Foundation,China (ZR2022JQ04)the Hunan Provincial Innovation Foundation For Postgraduate (CX20220993)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China (2019KFZ10).
文摘In this study,proton emission half-lives were investigated for deformed proton emitters with 53≤Z≤83based on the presented deformed Gamow-like model,where the deformation effect was included in the Coulomb potential.The experimental half-lives of proton emitters can be reproduced within a factor of 3.45.For comparison,the results from the universal decay law and the new Geiger-Nuttall law are also presented.Furthermore,the relevance of the half-lives to the angular momentum l for ^(117)La,^(121)Pr,^(135)Tb,and ^(141)Ho were analyzed,and the corresponding possible values of l were proposed:l=3,3,4,4.
基金Supported in part by the National Natural Science Foundation of China(12175100,11975132)the Construct Program of the Key Discipline in Hunan Province,the Research Foundation of Education Bureau of Hunan Province,China(22A0305,21B0402)+1 种基金the Natural Science Foundation of Hunan Province,China(2018JJ2321)the Innovation Group of Nuclear and Particle Physics in USC the Hunan Provincial Innovation Foundation for Postgraduate(CX20230962)。
文摘In this paper,using theαparticle preformation probabilities Pαfrom Xu et al.[Xu and Ren,Nucl.Phys.A 760,303(2005)],which were extracted by fitting experimental half-lives ofαdecay,based on a phenomenological harmonic oscillator potential model(HOPM)[Bayrak,J Phys G 47,025102(2020)],refitting 178αdecay half-lives of even-even nuclei obtained from the latest nuclear property table NUBASE2020,we obtain the only one adjustable parameter V0-162.6 MeV in the HOPM,i.e.,the depth of nuclear potential.The corresponding root-mean-square(rms)deviation isσ-0.322.Furthermore,to consider the contribution of centrifugal potential to unfavoredαdecay half-lives,adding a new term■(d and l are the adjustable parameter and orbital angular momentum carried away by emittedαparticle)to the logarithmic form of favoredαdecay half-lives under the HOPM framework,we propose an improved simple model(ISM)for calculating favored and unfavoredαdecay half-lives.Fitting the experimental half-lives of 205 unfavoredαdecay,we obtain d-0.381.The ISM is used to calculate the unfavoredαdecay half-lives of 128 odd-A and 77 odd-odd nuclei.The results improve by 54.2%and 53.6%,respectively,compared with HOPM.In addition,we extend the ISM to predict theαdecay half-lives of 144 nuclei with Z=117,118,119,and 120.For comparison,the improved model with eight parameters(DUR)proposed by Deng et al.[Deng,Phys.Rev.C 101,034307(2020)]and the modified universal decay law(MUDL)proposed by Soylu et al.[Soylu,Nucl.Phys.A 1013,122221(2021)]are also used.The predictions of these models and/or formulas are generally consistent with each other.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10535010, 10675090, 10775068, 10735010, 10975072and 11035001)the National Basic Research Program of China (GrantNos. 2007CB815004 and 2010CB327803)+1 种基金the Chinese Academy of Sciences Knowledge Innovation Project (Grant No. KJCX2-SW-N02)the Research Fund of Doctoral Point (RFDP) (Grant No. 20070284016)
文摘The α-decay properties of well-deformed even-even nuclei are systematically calculated within the multichannel cluster model (MCCM). Instead of working in the WKB framework, the quasibound solution to the coupled Schro¨dinger equation is presented with outgoing wave boundary conditions, and the coupling potential is taken into full account in terms of the general quantum theories. The calculated α-decay half-lives are found to agree well with the experimental data with a mean factor of less than 2. The fine structure observed in α decay is also well reproduced by the four-channel microscopic calculation. Very strikingly, the MCCM can give relatively precise descriptions of the branching ratio to excited 4+ states, which is often overestimated in the usual WKB calculations. We expect it to be a significant development of theoretical models toward quantitative descriptions of α transitions to high-spin daughter states.
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(Grant Nos.11490563 and 11375269)the National Basic Research Program of China(Grant No.2013CB834406)the National Key Research and Development Program of China(Grant No.2016YFA0400502)
文摘Experimental data ofβ--decay half-lives of nuclei with atomic number between 20 and 190 are investigated.A systematic formula has been proposed to calculateβ^--decay half-lives of neutron-rich nuclei,with a particular consideration on shell and pair effects,the decay energy Q as well as the nucleon numbers(Z,N).Although the formula has relatively few parameters,it reproduces the experimentalβ^--decay half-lives of neutron-rich nuclei very well.The predicted half-lives for the r-process relevant nuclei obtained with the current formula serve as reliable input in the r-process model calculations.
基金supported by the National Natural Science Foundation of China(Grants Nos.10735010,10975072,11035001,11120101005 and 11165006)the National Major State Basic Research and Development of China(Grants Nos.2013CB834400 and 2010CB327803)+2 种基金CAS Knowledge Innovation Project(Grant No.KJCX2-SW-N02)the Research Fund of Doctoral Point(RFDP)(Grants No.20100091110028)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘We investigate the half-lives of β + /EC(electron capture) decay using the proton-neutron quasiparticle random-phase approximation(pnQRPA) with a δ-form Gamow-Teller residual interaction.Both particle-hole and particle-particle residual interactions are consistently introduced in dealing with the pnQRPA matrix equation.The sensitivity of the calculated half-lives to some physical quantities used in the calculations is examined.Calculations are performed for even-even neutron-deficient isotopes ranging from Z = 10 to Z = 76.Good agreement between experiment and theory is achieved especially for the nuclei far from stability,and the results of our calculations are discussed with comparison with other theoretical results.Predictions on the β-decay half-lives of some very neutron-deficient nuclei are also given for reference in future experiments.
基金Supported in part by the National Natural Science Foundation of China(12175100,11975132)the Construct Program of the Key Discipline in Hunan Province,the Research Foundation of the Education Bureau of Hunan Province,China(18A237)+2 种基金the Natural Science Foundation of Shandong Province,China(ZR2022JQ04)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(2019KFZ10)the Innovation Group of Nuclear and Particle Physics in USC,the Innovation Foundation for Postgraduate of Hunan Province,China(CX20230962)。
文摘In this study,considering the modified preformation probability P_(c)to be log_(10)P_(c)=(A_(c)−1)/3log_(10)P_(α)+c′,where P_(α)and c′are theα-particle preformation probability and an adjustable parameter proposed by Wang et al.[Chin.Phys.C 45,044111(2021)],respectively,we extend a new simple model put forward by Bayrak[J.Phys.G 47,025102(2020)]to systematically study the cluster radioactivity half-lives of 28 trans-lead nuclei ranging from^(222)Fr to^(242)Cm,which is based on the Wentzel-Kramers-Brillouin approximation and Bohr–Sommerfeld quantization condition.For comparison,a universal decay law proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a three-parameter model-independent formula put forward by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and the semi-empirical model proposed by Tavares et al.[Eur.Phys.J.A 49,1(2013)]are used.Our calculated results reproduce the experimental data well,with a standard deviation of 0.818.Furthermore,we use this model to predict the cluster radioactivity half-lives of 51 possible cluster radioactive candidates whose cluster radioactivities are energetically allowed or observed but not yet quantified in NUBASE2020.
基金Supported in part by the National Natural Science Foundation of China(12175100,11975132)the construct program of the key discipline in hunan province+4 种基金the Research Foundation of Education Bureau of Hunan Province,China(18A237)the Shandong Province Natural Science Foundation,China(ZR2022JQ04)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(2019KFZ10)the Innovation Group of Nuclear and Particle Physics in USCHunan Provincial Innovation Foundation for Postgraduate(CX20210942)。
文摘In this study,derived from Balasubramaniam’s formula[Phys.Rev.C 70,017301(2004)]and further considering the effect of the parent nucleus mass,blocking effect,and effect of reduced mass on cluster radioactivity half-lives,we propose a new Geiger-Nuttall law that is model-independent to systematically evaluate the halflives of this process for 16 even-even nuclei and 10 odd-A nuclei.For comparison,a single universal curve for cluster radioactivity andαdecay proposed by Poenaru[Phys.Rev.C 83,014601(2011)],a scaling law proposed by Horoi[J.Phys.G:Nucl.Part.Phys.30,945(2004)],an extension of the Viola-Seaborg formula fromαdecay to cluster radioactivity proposed by Ren et al.[Phys.Rev.C 70,034304(2004)],a new semi-empirical formula for exotic cluster decay proposed by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and a unified formula for the half-lives ofαdecay and cluster radioactivity proposed by Ni et al.[Phys.Rev.C 78,044310(2008)]are also used.The calculated results of our new Geiger-Nuttall law are in good agreement with the experimental half-lives,with the least rms being 0.606,and are better than the compared values.Moreover,we extend this formula to predict the cluster radioactivity half-lives of 51 nuclei whose decay energies are energetically allowed or observed but not yet quantified in NUBASE2020.
基金Supported in part by the National Natural Science Foundation of China(12175100,11975132)the Construct Program of the Key Discipline in Hunan Province,the Research Foundation of Education Bureau of Hunan Province,China(21B0402,18A237)+2 种基金the Natural Science Foundation of Hunan Province,China(2018JJ2321),the Innovation Group of Nuclear and Particle Physics in USC,the Natural Science Foundation of Shandong Province,China(ZR2022JQ04)the Innovation Foundation for Postgraduate of Hunan Province,China(CX20220993)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(2019KFZ10)。
文摘In this study,based on Wentzel-Kramers-Brillouin theory,we systematically investigate the cluster radioactivity half-lives of 22 nuclei ranging from^(221)Fr to^(242)Cm using a phenomenological model that considers the screened electrostatic effect of the Coulomb potential.In this model,there are two adjustable parameters,t and g,which are related to the screened electrostatic barrier and the strength of the spectroscopic factor,respectively.The calculated results indicate that this model can effectively reproduce the experimental data,with a corresponding rootmean-square deviation of 0.660.In addition,we extend this model to predict the half-lives of possible cluster radioactive candidates whose cluster radioactivities are energetically allowed or observed but not yet quantified in the evaluated nuclear properties table NUBASE2020.The predicted results are consistent with those obtained using other theoretical models and/or empirical formulas,including the universal decay law proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a semi-empirical model for bothαdecay and cluster radioactivity proposed by Santhosh et al.[J.Phys.G 35,085102(2008)],and a unified formula for the half-lives ofαdecay and cluster radioactivity proposed by Ni et al.[Phys.Rev.C 78,044310(2008)].
基金supported in part by the National Natura Science Foundation of China(12175100 and 11975132)the Construct Program of the Key Discipline in Hunan Province+5 种基金the Research Foundation of Education Bureau of Hunan Province(18A237)the Natural Science Foundation of Hunan Province(2018JJ3324)the Innovation Group of Nuclear and Particle Physics in USCthe Shandong Province Natural Science Foundation(ZR2015AQ007)the National Innovation Training Foundation of China(201910555161)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(2019KFZ10)。
文摘In the present work,based on the Wentzel-Kramers-Brillouin(WKB)theory,considering the cluster preformation probability(Pc),we systematically investigate the cluster radioactivity half-lives of 22 trans-lead nuclei ranging from221Fr to242Cm.When the mass number of the emitted cluster Ac<28,Pcis obtained by the exponential relationship of Pcto theαdecay preformation probability(Pα)proposed by R.Blendowskeis et al.[Phys.Rev.Lett.61,1930(1988)],while Pαis calculated through the cluster-formation model(CFM).When Ac≥28,Pcis calculated through the charge-number dependence of Pcon the decay products proposed by Ren et al.[Phys.Rev.C70,034304(2004)].The half-lives of cluster radioactivity have been calculated by the density-dependent cluster model[Phys.Rev.C 70,034304(2004)]and by the unified formula of half-lives for alpha decay and cluster radioactivity[Phys.Rev.C 78,044310(2008)].For comparison,a universal decay law(UDL)proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a semi-empirical model for bothαdecay and cluster radioactivity proposed by Santhosh[J.Phys.G:Nucl.Part.Phys.35,085102(2008)],and a unified formula of half-lives for alpha decay and cluster radioactivity[Phys.Rev.C 78,044310(2008)]are also used.The calculated results of our work,Ni’s formula,and the UDL can well reproduce the experimental data and are better than those of Santhosh’s model.In addition,we extend this model to predict the half-lives for 51 nuclei,whose cluster radioactivity is energetically allowed or observed but not yet quantified in NUBASE2020.
基金supported by the National Natural Science Foundation of China(Grant Nos.11035001,10975072,11120101005,11175085 and11375086)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Nuclear double β^--decays with two neutrinos were observed for many years and a systematic law describing the relation between their half-lives and decay energies was also proposed recently [Phys Rev C, 2014, 89： 064603]. However, double β^＋ -decay （β^＋β^＋） with emission of both two positrons and two neutrinos has not been observed up to date. In this article, we pcrform a systematic analysis on the candidates of double β^＋-decay, based on the 2012 nuclear mass table. Eight nuclei are found to be the good candidates for double β^＋-decay and their half-lives are predicted according to the generalization of the systematic law to double β^＋-decay. As far as we know, there is no theoretical result on double β^＋-decay of nucleus ^154Dy and our result is the first prediction on this nucleus. This is also the first complete research on eight double β^＋-decay candidates based on the available data of nuclear masses. It is expected that the calculated half-lives of double β^＋-decay in this article will be useful for future experimental search of double β^＋-decay.
