During the last few decades,rare isotope beam facilities have provided unique data for studying the properties of nuclides located far from the beta-stability line.Such nuclei are often accompanied by exotic structure...During the last few decades,rare isotope beam facilities have provided unique data for studying the properties of nuclides located far from the beta-stability line.Such nuclei are often accompanied by exotic structures and radioactive modes,which represent the forefront of nuclear research.Among them,two-proton(2p)radioactivity is a rare decay mode found in a few highly proton-rich isotopes.The 2p decay lifetimes and properties of emitted protons hold invaluable information regarding the nuclear structures in the presence of a low-lying proton continuum;as such,they have attracted considerable research attention.In this review,we present some of the recent experimental and theoretical progress regarding the 2p decay,including technical innovations for measuring nucleon-nucleon correlations and developments in the models that connect their structural aspects with their decay properties.This impressive progress should play a significant role in elucidating the mechanism of these exotic decays,probing the corresponding components inside nuclei,and providing deep insights into the open quantum nature of dripline systems.展开更多
The effect of source size and emission time on the proton-proton(p-p)momentum correlation function(Cpp(q))has been studied systematically.Assuming a spherical Gaussian source with space and time profile according to t...The effect of source size and emission time on the proton-proton(p-p)momentum correlation function(Cpp(q))has been studied systematically.Assuming a spherical Gaussian source with space and time profile according to the function S(r,t)~exp(-r2/2 r02-t/τ)in the correlation function calculation code(CRAB),the results indicate that one Cpp(q)distribution corresponds to a unique combination of source size r0 and emission timeτ.Considering the possible nuclear deformation from a spherical nucleus,an ellipsoidal Gaussian source characterized by the deformation parameter∈=ΔR/R has been simulated.There is almost no difference of Cpp(q)between the results of spherically and ellipsoidally shaped sources with small deformation.These results indicate that a unique source size r0 and emission time could be extracted from the p-p momentum correlation function,which is especially important for identifying the mechanism of twoproton emission from proton-rich nuclei.Furthermore,considering the possible existence of cluster structures within a nucleus,the double Gaussian source is assumed.The results show that the p-p momentum correlation function for a source with or without cluster structures has large systematical differences with the variance of r0 andτ.This may provide a possible method for experimentally observing the cluster structures in proton-rich nuclei.展开更多
Two-proton radioactivity from18Ne is discussed in terms of sequential decay.The branch ratios for oneproton emission from excited states are calculated,which including spectroscopic factors,obtained from a Shellmodel ...Two-proton radioactivity from18Ne is discussed in terms of sequential decay.The branch ratios for oneproton emission from excited states are calculated,which including spectroscopic factors,obtained from a Shellmodel calculation with realistic interactions.The branch ratios show that the two-proton emission from the 1-state of 18Ne at 7.94 MeV is most likely to go through the sequential decay.The same mechanism is discussed for other excited states at higher energy by different interactions.展开更多
In this work,considering the preformation factor of the emitted two protons in parent nucleus S_(2p) and the effect of the parent nucleus deformation,based on the Wentzel-Kramers-Brillouin approximation and Bohr-Somme...In this work,considering the preformation factor of the emitted two protons in parent nucleus S_(2p) and the effect of the parent nucleus deformation,based on the Wentzel-Kramers-Brillouin approximation and Bohr-Sommerfeld quantization condition,we improve a simple phenomenological model proposed by Bayrak[J.Phys.G:47,025102(2020)]to systematically study 2p radioactivity half-lives.This model contains two adjustable parameters V_(0) and a_(β),which are related to the depth of nuclear potential and effect of deformation.The calculated results show that this model can effectively reproduce the experimental data with a corresponding root-mean-square(RMS)standard deviation of σ=0.683.For comparison,we include the Gamow-like model(GLM)proposed by Liu et al.[Chin.Phys.C 45,044110(2021)],generalized liquid drop model(GLDM)proposed by Cui et al.[Phys.Rev.C 101,014301(2020)],effective liquid drop model(ELDM)proposed by M.Gonalves et al.[Phys.Lett.B 774,14(2017)],two-potential approach with Skyrme-Hartree-Fock(TPASHF)proposed by Pan et al.[Chin.Phys.C 45,124104(2021)],phenomenological model with a screened electrostatic barrier(SEB)propoesed by Zou et al.[Chin.Phys.C 45,104101(2021)],unified fission model(UFM)proposed by Xing et al.[Chin.Phys.C 45,124105(2021)],Coulomb and proximity potential model for deformed nuclei(CPPMDN)proposed by Santhosh[Phys.Rev.C 104,064613(2021)],two-parameter empirical formula proposed by Liu et al.[Chin.Phys.C 45,024108(2021)],and four-parameter empirical formula proposed by Sreeja et al.[Eur.Phys.J.A 55,33(2019)].In addition,we use this model to 2p predict the radioactive half-lives of some possible potential nuclei whose 2p radioactivity are energetically allowed or observed but not yet quantified in NUBASE2020.展开更多
The tensor force and pairing correlation effects on the two-proton radioactivity of^(18)Mg and^(20)Si with a pronounced two-proton halo are explored in the framework of spherical Skyrme-Hartree-Fock-Bogoliubov theory....The tensor force and pairing correlation effects on the two-proton radioactivity of^(18)Mg and^(20)Si with a pronounced two-proton halo are explored in the framework of spherical Skyrme-Hartree-Fock-Bogoliubov theory.It is shown that the halo sizes are enhanced with the increase in the strength of the tensor force and pairing correlation.Furthermore,the increasing halo sizes lead to the enhancement of diproton emission.Then,the tensor force is found to have a small influence on the two-proton decay energies,and the two-proton decay energies calculated with strong surface pairing are smaller than those with weak mixed pairing.Because the two-proton decay energies are relat-ively large,the predicted order of magnitude of half-lives within the effective liquid drop model is not sensitive to the decay energy variation caused by the tensor force and pairing correlation,which has a value of approximately 10^(-18)s.展开更多
Two-proton emissions from the excited states of 17,18Ne, 28P and 28,29S were investigated experimentally by the radioactive beams bombarding on the 197Au target via the Coulomb excitation. The complete-kinematics meas...Two-proton emissions from the excited states of 17,18Ne, 28P and 28,29S were investigated experimentally by the radioactive beams bombarding on the 197Au target via the Coulomb excitation. The complete-kinematics measurements were actualized by the stacks of silicon-strip detectors and CsI+PIN array detectors. The invariant mass of final systems as well as the relative momentum, opening angle, and relative energy of the two emitted protons was reconstructed under the framework of relativ istic kinematics. Visible proton-proton correlations were observed in these systems. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like He cluster emission, three-body 2 phase-space decay, and two-body sequential decay were taken into account. With the help of Monte-Carlo simulations, the two protons emitted from the 6.15 MeV excited state of Ne and the excited states in the energy region of 9.6–10.4 MeV of S, 18 29 respectively, exhibited prominent features of2 He cluster decay while for the other cases, no obvious diproton emissions were observed.展开更多
Proton(p) and two-proton(2p) emissions from the proton-rich nuclei with 10≤Z≤20 have been explored by the in-fight decay and implantation decay methods, respectively, in a series of experiments at the HIRFL-RIBLL fa...Proton(p) and two-proton(2p) emissions from the proton-rich nuclei with 10≤Z≤20 have been explored by the in-fight decay and implantation decay methods, respectively, in a series of experiments at the HIRFL-RIBLL facility. The in-flight 2p emissions from the excited states of ^(28,29)S/^(26,27)P and ^(17,18)Ne were studied by complete-kinematics measurements. Mechanisms of 2p decay and related p-p correlations have been explored. Obvious 2p correlated emissions have been observed in the cases of ^(28,29)S but not in ^(27,28)P, indicating the 2p halo plays an important role in the diproton emission. In the ^(17,18)Ne cases, a small 2p opening angles were deduced by the HBT analyses, implying the BCS-BEC crossover may occur in the dilute nuclear matter. Moreover,^(27)S/^(26)P/^(25)Si,^(22)Si/^(20)Mg,^(23)Si/^(22)Al/^(21)Mg,^(24)Si/^(23)Al, and ^(36,37)Ca were implanted in a thin double-sided-silicon-strip detector and their β-delayed p and 2p decays have been measured by a surrounding silicon detector array under the continuous-beam mode. Important information on the nuclear spectroscopy, such as energy, lifetime, branching-ratio, and so on, has been extracted, which helps us to understand the nuclear structures of proton-rich exotic nuclei close to the drip-line.展开更多
A unified fission model is extended to study two-proton radioactivity of the ground states of nuclei,and a good agreement between the experimental and calculated half-lives is found.The two-proton radioactivity half-l...A unified fission model is extended to study two-proton radioactivity of the ground states of nuclei,and a good agreement between the experimental and calculated half-lives is found.The two-proton radioactivity half-lives of the ground states of some probable candidates are predicted within this model by inputting the released energies taken from the AME2020 table.It is shown that the predictive accuracy of the half-lives is comparable to those of other models.Then,two-proton radioactivity of the excited states of^(14)O,^(17,18)Ne,^(22)Mg,^(29)S,and^(94)Ag is discussed within the unified fission model and two analytical formulas.It is found that the experimental half-lives of the excited states are reproduced better within the unified fission model.Furthermore,the two formulas are not suitable for the study of two-proton radioactivity of excited states because their physical appearance deviates from the mechanism of quantum tunneling,and the parameters involved are obtained without including experimental data from the excited states.展开更多
We calculate the two-proton decay width of the6 Be nucleus employing the schematic densitydependent contact potential for the proton-proton pairing interaction. The decay width is calculated with a time-dependent meth...We calculate the two-proton decay width of the6 Be nucleus employing the schematic densitydependent contact potential for the proton-proton pairing interaction. The decay width is calculated with a time-dependent method, in which the two-proton emission is described as a time-evolution of a threebody meta-stable state. Model-dependence of the two-proton decay width has been shown by comparing the results obtained with the two different pairing models, schematic density-dependent contact and Minnesota interactions, which have zero and finite ranges, respectively.展开更多
In this work,we systematically study the two-proton(2_(p))radioactivity half-lives using the two-potential approach,and the nuclear potential is obtained using the Skyrme-Hartree-Fock approach and the Skyrme effective...In this work,we systematically study the two-proton(2_(p))radioactivity half-lives using the two-potential approach,and the nuclear potential is obtained using the Skyrme-Hartree-Fock approach and the Skyrme effective interaction of SLy8.For true 2_(p) radioactivity(Q2_(p)>0 and Q_(p)<0,where Q_(p) and Q2_(p) are the released energies of the one-proton and two-proton radioactivity,respectively),the standard deviation between the experimental half-lives and our theoretical calculations is 0.701.In addition,we extend this model to predict the half-lives of 15 possible 2_(p) radioactivity candidates with Q2_(p)>0 obtained from the evaluated atomic mass table AME2016.The calcu-lated results indicate a clear linear relationship between the logarithmic 2_(p) radioactivity half-lives(logio10T_(1/2))and coulomb parameters[(Z_(d)^(0.8)+l^(0.25))Q_(2_(p))^(-1/2)]considering the effect of orbital angular momentum proposed by Liu et al.[Chin.Phys.C 45,024108(2021)].For comparison,the generalized liquid drop model(GLDM),effective liquid drop model(ELDM),and Gamow-like model are also used.Our predicted results are consistent with those obtained using other relevant models.展开更多
In this study,based on the Gamow-like model,we systematically analyze two-proton(2p) radioactivity half-lives of nuclei near or beyond the proton drip line.It is found that the calculated results can reproduce experim...In this study,based on the Gamow-like model,we systematically analyze two-proton(2p) radioactivity half-lives of nuclei near or beyond the proton drip line.It is found that the calculated results can reproduce experimental data well.Furthermore,using this model,we predict the half-lives of possible 2p radioactivity candidates whose 2p radioactivity is energetically allowed or observed but not yet quantified in the latest table of evaluated nuclear properties,i.e.,NUBASE2016.The predicted results are in good agreement with those from other theoretical models and empirical formulas,namely the effective liquid drop model(ELDM),generalized liquid drop model(GLDM),Sreej a formula,and Liu formula.展开更多
In the present work,a two-parameter empirical formula is proposed,based on the Geiger-Nuttall law,to study two-proton( 2p )radioactivity.Using this formula,the calculated 2p radioactivity half-lives are in good agreem...In the present work,a two-parameter empirical formula is proposed,based on the Geiger-Nuttall law,to study two-proton( 2p )radioactivity.Using this formula,the calculated 2p radioactivity half-lives are in good agreement with the experimental data as well as with calculated results obtained by Goncalves et al.[Phys.Lett.B 774,14(2017)]using the effective liquid drop model(ELDM),Sreeja et al.[Eur.Phys.J.A 55,33(2019)]using a four-parameter empirical formula,and Cui et al.[Phys.Rev.C 101:014301(2020)]using a generalized liquid drop model(GLDM).In addition,this two-parameter empirical formula is extended to predict the half-lives of 22 possible 2p radioactivity candidates with 2p radioactivity released energy Q_(2p)>0 ,obtained from the latest evaluated atomic mass table AME2016.The predicted results are highly consistent with those obtained using other theoretical models such as the ELDM,GLDM and four-parameter empirical formula.展开更多
Considering the preformation probability of the two emitted protons in the parent nucleus,we extend the Coulomb and proximity potential model(CPPM)to systematically study two-proton(2p)radioactivity half-lives of the ...Considering the preformation probability of the two emitted protons in the parent nucleus,we extend the Coulomb and proximity potential model(CPPM)to systematically study two-proton(2p)radioactivity half-lives of the nuclei close to proton drip line.The proximity potential chosen is Prox.81 proposed by Blocki et al.in 1981.Furthermore,we apply this model to predict the half-lives of possible 2p radioactive candidates whose 2p radioactivity is energetically allowed or observed but not yet quantified in the evaluated nuclear properties table NUBASE2016.The predicted results are in good agreement with those from other theoretical models and empirical formulas,namely the effective liquid drop model(ELDM),generalized liquid drop model(GLDM),Gamow-like model,Sreeja formula and Liu formula.展开更多
The recently discovered,extremely proton-rich nuclide 18 Mg exhibits ground-state decay via two sequential two-proton(2p)emissions through the intermediate nucleus,16Ne.This study investigates the structure and the in...The recently discovered,extremely proton-rich nuclide 18 Mg exhibits ground-state decay via two sequential two-proton(2p)emissions through the intermediate nucleus,16Ne.This study investigates the structure and the initial 2p decay mechanism of^(18)Mgby examining the density and correlations of the valence protons using a three-body Gamow coupled-channel method.The results show that the ground state of^(18)Mgis significantly influenced by the continuum,resulting in a significant s-wave component.However,based on the current framework,this does not lead to a significant deviation in mirror symmetry in either the structure or spectroscopy of the 18Mg-18C pair.Additionally,the time evolution analysis of the^(18)Mgground state suggests a simultaneous 2p emission during the first step of decay.The observed nucleon-nucleon correlations align with those of the light-mass 2p emitters,indicating a consistent decay behavior within this nuclear region.展开更多
基金partially supported by the National Natural Science Foundation of China (Nos. 12147101, 11925502,11935001,11961141003, 11890714)the National Key R&D Program of China (No.2018YFA0404404)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDB34030000)the Shanghai Development Foundation for Science and Technology(No. 19ZR1403100)
文摘During the last few decades,rare isotope beam facilities have provided unique data for studying the properties of nuclides located far from the beta-stability line.Such nuclei are often accompanied by exotic structures and radioactive modes,which represent the forefront of nuclear research.Among them,two-proton(2p)radioactivity is a rare decay mode found in a few highly proton-rich isotopes.The 2p decay lifetimes and properties of emitted protons hold invaluable information regarding the nuclear structures in the presence of a low-lying proton continuum;as such,they have attracted considerable research attention.In this review,we present some of the recent experimental and theoretical progress regarding the 2p decay,including technical innovations for measuring nucleon-nucleon correlations and developments in the models that connect their structural aspects with their decay properties.This impressive progress should play a significant role in elucidating the mechanism of these exotic decays,probing the corresponding components inside nuclei,and providing deep insights into the open quantum nature of dripline systems.
基金supported by the National Key R&D Program of China(No.2018YFA0404404)the National Natural Science Foundation of China(Nos.11925502,11935001,11961141003,11421505,11475244,and 11927901)+2 种基金the Shanghai Development Foundation for Science and Technology(No.19ZR1403100)the Strategic Priority Research Program of the CAS(No.XDB34030000)the Key Research Program of Frontier Sciences of the CAS(No.QYZDJ-SSW-SLH002).
文摘The effect of source size and emission time on the proton-proton(p-p)momentum correlation function(Cpp(q))has been studied systematically.Assuming a spherical Gaussian source with space and time profile according to the function S(r,t)~exp(-r2/2 r02-t/τ)in the correlation function calculation code(CRAB),the results indicate that one Cpp(q)distribution corresponds to a unique combination of source size r0 and emission timeτ.Considering the possible nuclear deformation from a spherical nucleus,an ellipsoidal Gaussian source characterized by the deformation parameter∈=ΔR/R has been simulated.There is almost no difference of Cpp(q)between the results of spherically and ellipsoidally shaped sources with small deformation.These results indicate that a unique source size r0 and emission time could be extracted from the p-p momentum correlation function,which is especially important for identifying the mechanism of twoproton emission from proton-rich nuclei.Furthermore,considering the possible existence of cluster structures within a nucleus,the double Gaussian source is assumed.The results show that the p-p momentum correlation function for a source with or without cluster structures has large systematical differences with the variance of r0 andτ.This may provide a possible method for experimentally observing the cluster structures in proton-rich nuclei.
基金Supported by the Funda o para a Ciência e a Techologia(Portugal),Project:PTDC/FIS/68340/2006 and CERN/FP/116385/2010
文摘Two-proton radioactivity from18Ne is discussed in terms of sequential decay.The branch ratios for oneproton emission from excited states are calculated,which including spectroscopic factors,obtained from a Shellmodel calculation with realistic interactions.The branch ratios show that the two-proton emission from the 1-state of 18Ne at 7.94 MeV is most likely to go through the sequential decay.The same mechanism is discussed for other excited states at higher energy by different interactions.
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)+3 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 work,considering the preformation factor of the emitted two protons in parent nucleus S_(2p) and the effect of the parent nucleus deformation,based on the Wentzel-Kramers-Brillouin approximation and Bohr-Sommerfeld quantization condition,we improve a simple phenomenological model proposed by Bayrak[J.Phys.G:47,025102(2020)]to systematically study 2p radioactivity half-lives.This model contains two adjustable parameters V_(0) and a_(β),which are related to the depth of nuclear potential and effect of deformation.The calculated results show that this model can effectively reproduce the experimental data with a corresponding root-mean-square(RMS)standard deviation of σ=0.683.For comparison,we include the Gamow-like model(GLM)proposed by Liu et al.[Chin.Phys.C 45,044110(2021)],generalized liquid drop model(GLDM)proposed by Cui et al.[Phys.Rev.C 101,014301(2020)],effective liquid drop model(ELDM)proposed by M.Gonalves et al.[Phys.Lett.B 774,14(2017)],two-potential approach with Skyrme-Hartree-Fock(TPASHF)proposed by Pan et al.[Chin.Phys.C 45,124104(2021)],phenomenological model with a screened electrostatic barrier(SEB)propoesed by Zou et al.[Chin.Phys.C 45,104101(2021)],unified fission model(UFM)proposed by Xing et al.[Chin.Phys.C 45,124105(2021)],Coulomb and proximity potential model for deformed nuclei(CPPMDN)proposed by Santhosh[Phys.Rev.C 104,064613(2021)],two-parameter empirical formula proposed by Liu et al.[Chin.Phys.C 45,024108(2021)],and four-parameter empirical formula proposed by Sreeja et al.[Eur.Phys.J.A 55,33(2019)].In addition,we use this model to 2p predict the radioactive half-lives of some possible potential nuclei whose 2p radioactivity are energetically allowed or observed but not yet quantified in NUBASE2020.
基金Supported by the National Natural Science Foundation of China(U1832120,11675265)the Natural Science Foundation for Outstanding Young Scholars of Hebei Province,China(A2020210012)+4 种基金the Natural Science Foundation of Hebei Province,China(A2021210010)the Key Laboratory of High Precision Nuclear Spectroscopy,Institute of Modern Physics,Chinese Academy of Sciences(IMPKFKT2021002)the Graduate Student Innovative Research Project of Shijiazhuang Tiedao University(YC2022062)the Continuous Basic Scientific Research Project(WDJC-2019-13)the Leading Innovation Project(LC 192209000701).
文摘The tensor force and pairing correlation effects on the two-proton radioactivity of^(18)Mg and^(20)Si with a pronounced two-proton halo are explored in the framework of spherical Skyrme-Hartree-Fock-Bogoliubov theory.It is shown that the halo sizes are enhanced with the increase in the strength of the tensor force and pairing correlation.Furthermore,the increasing halo sizes lead to the enhancement of diproton emission.Then,the tensor force is found to have a small influence on the two-proton decay energies,and the two-proton decay energies calculated with strong surface pairing are smaller than those with weak mixed pairing.Because the two-proton decay energies are relat-ively large,the predicted order of magnitude of half-lives within the effective liquid drop model is not sensitive to the decay energy variation caused by the tensor force and pairing correlation,which has a value of approximately 10^(-18)s.
基金supported by the National Natural Science Foundation of China(Grant Nos. 10675169, 10735100, and 10727505)the Major State Basic Research Developing Program (Grant No. 2007CB815003)
文摘Two-proton emissions from the excited states of 17,18Ne, 28P and 28,29S were investigated experimentally by the radioactive beams bombarding on the 197Au target via the Coulomb excitation. The complete-kinematics measurements were actualized by the stacks of silicon-strip detectors and CsI+PIN array detectors. The invariant mass of final systems as well as the relative momentum, opening angle, and relative energy of the two emitted protons was reconstructed under the framework of relativ istic kinematics. Visible proton-proton correlations were observed in these systems. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like He cluster emission, three-body 2 phase-space decay, and two-body sequential decay were taken into account. With the help of Monte-Carlo simulations, the two protons emitted from the 6.15 MeV excited state of Ne and the excited states in the energy region of 9.6–10.4 MeV of S, 18 29 respectively, exhibited prominent features of2 He cluster decay while for the other cases, no obvious diproton emissions were observed.
基金National Basic Research Program of China(973 Program)(2013CB834404)National Natural Science Foundation of China(10735100,10727505,11005156,U1432246,U1432127)
文摘Proton(p) and two-proton(2p) emissions from the proton-rich nuclei with 10≤Z≤20 have been explored by the in-fight decay and implantation decay methods, respectively, in a series of experiments at the HIRFL-RIBLL facility. The in-flight 2p emissions from the excited states of ^(28,29)S/^(26,27)P and ^(17,18)Ne were studied by complete-kinematics measurements. Mechanisms of 2p decay and related p-p correlations have been explored. Obvious 2p correlated emissions have been observed in the cases of ^(28,29)S but not in ^(27,28)P, indicating the 2p halo plays an important role in the diproton emission. In the ^(17,18)Ne cases, a small 2p opening angles were deduced by the HBT analyses, implying the BCS-BEC crossover may occur in the dilute nuclear matter. Moreover,^(27)S/^(26)P/^(25)Si,^(22)Si/^(20)Mg,^(23)Si/^(22)Al/^(21)Mg,^(24)Si/^(23)Al, and ^(36,37)Ca were implanted in a thin double-sided-silicon-strip detector and their β-delayed p and 2p decays have been measured by a surrounding silicon detector array under the continuous-beam mode. Important information on the nuclear spectroscopy, such as energy, lifetime, branching-ratio, and so on, has been extracted, which helps us to understand the nuclear structures of proton-rich exotic nuclei close to the drip-line.
基金Supported by the National Natural Science Foundation of China (U1832120, 11675265)the Natural Science Foundation for Outstanding Young Scholars of Hebei Province of China (A2020210012, A2018210146)+1 种基金the Natural Science Foundation of Hebei Province of China (A2021210010)the Continuous Basic Scientific Research Project (WDJC-2019-13) and the Leading Innovation Project (LC 192209000701)
文摘A unified fission model is extended to study two-proton radioactivity of the ground states of nuclei,and a good agreement between the experimental and calculated half-lives is found.The two-proton radioactivity half-lives of the ground states of some probable candidates are predicted within this model by inputting the released energies taken from the AME2020 table.It is shown that the predictive accuracy of the half-lives is comparable to those of other models.Then,two-proton radioactivity of the excited states of^(14)O,^(17,18)Ne,^(22)Mg,^(29)S,and^(94)Ag is discussed within the unified fission model and two analytical formulas.It is found that the experimental half-lives of the excited states are reproduced better within the unified fission model.Furthermore,the two formulas are not suitable for the study of two-proton radioactivity of excited states because their physical appearance deviates from the mechanism of quantum tunneling,and the parameters involved are obtained without including experimental data from the excited states.
文摘We calculate the two-proton decay width of the6 Be nucleus employing the schematic densitydependent contact potential for the proton-proton pairing interaction. The decay width is calculated with a time-dependent method, in which the two-proton emission is described as a time-evolution of a threebody meta-stable state. Model-dependence of the two-proton decay width has been shown by comparing the results obtained with the two different pairing models, schematic density-dependent contact and Minnesota interactions, which have zero and finite ranges, respectively.
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+5 种基金the Research Foundation of Education Bureau of Hunan Province,China (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 (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 this work,we systematically study the two-proton(2_(p))radioactivity half-lives using the two-potential approach,and the nuclear potential is obtained using the Skyrme-Hartree-Fock approach and the Skyrme effective interaction of SLy8.For true 2_(p) radioactivity(Q2_(p)>0 and Q_(p)<0,where Q_(p) and Q2_(p) are the released energies of the one-proton and two-proton radioactivity,respectively),the standard deviation between the experimental half-lives and our theoretical calculations is 0.701.In addition,we extend this model to predict the half-lives of 15 possible 2_(p) radioactivity candidates with Q2_(p)>0 obtained from the evaluated atomic mass table AME2016.The calcu-lated results indicate a clear linear relationship between the logarithmic 2_(p) radioactivity half-lives(logio10T_(1/2))and coulomb parameters[(Z_(d)^(0.8)+l^(0.25))Q_(2_(p))^(-1/2)]considering the effect of orbital angular momentum proposed by Liu et al.[Chin.Phys.C 45,024108(2021)].For comparison,the generalized liquid drop model(GLDM),effective liquid drop model(ELDM),and Gamow-like model are also used.Our predicted results are consistent with those obtained using other relevant models.
基金Supported in part by the National Natural Science Foundation of China(11205083,11975132)the Construct Program of the Key Discipline in Hunan Province+5 种基金the Research Foundation of Education Bureau of Hunan Province,China(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(ZR2019YQ01)the Hunan Provincial Innovation Foundation For Postgraduate(CX20200909)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 the Gamow-like model,we systematically analyze two-proton(2p) radioactivity half-lives of nuclei near or beyond the proton drip line.It is found that the calculated results can reproduce experimental data well.Furthermore,using this model,we predict the half-lives of possible 2p radioactivity candidates whose 2p radioactivity is energetically allowed or observed but not yet quantified in the latest table of evaluated nuclear properties,i.e.,NUBASE2016.The predicted results are in good agreement with those from other theoretical models and empirical formulas,namely the effective liquid drop model(ELDM),generalized liquid drop model(GLDM),Sreej a formula,and Liu formula.
基金Supported in part by the National Naurll Science Foundation of China(11205083,11505100,11705055)the Construct Program of the Key Discipline in Hunan Provinee,the Research Foundation of Education Bureau of Hunan Province,China(15A I59,18A237)+4 种基金the Natural Science Foundation of Hunan Province,China(2015JJ3103,2015JJ2121,2018JJ2321)the Innovation Group of Nuclear and Particle Physics in UsSC,the Shandong Provinee Natural Science Foundation,China(ZR2015AQ007)the Hunan Provincial Innovation Foundation For Posigraduate(CX20200909)the National Innovation Training Foundation of China(201910555161)the Opening Projeet of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment.University of South China(2019KFZ10)。
文摘In the present work,a two-parameter empirical formula is proposed,based on the Geiger-Nuttall law,to study two-proton( 2p )radioactivity.Using this formula,the calculated 2p radioactivity half-lives are in good agreement with the experimental data as well as with calculated results obtained by Goncalves et al.[Phys.Lett.B 774,14(2017)]using the effective liquid drop model(ELDM),Sreeja et al.[Eur.Phys.J.A 55,33(2019)]using a four-parameter empirical formula,and Cui et al.[Phys.Rev.C 101:014301(2020)]using a generalized liquid drop model(GLDM).In addition,this two-parameter empirical formula is extended to predict the half-lives of 22 possible 2p radioactivity candidates with 2p radioactivity released energy Q_(2p)>0 ,obtained from the latest evaluated atomic mass table AME2016.The predicted results are highly consistent with those obtained using other theoretical models such as the ELDM,GLDM and four-parameter empirical formula.
基金Supported 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(18A237)the Natural Science Foundation of Hunan Province,China(2015JJ3103,2018JJ2321)the Innovation Group of Nuclear and Particle Physics in USCthe Shandong Province Natural Science Foundation,China(ZR2019YQ01)Hunan Provincial Innovation Foundation For Postgraduate(CX20210942)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(2019KFZ10)。
文摘Considering the preformation probability of the two emitted protons in the parent nucleus,we extend the Coulomb and proximity potential model(CPPM)to systematically study two-proton(2p)radioactivity half-lives of the nuclei close to proton drip line.The proximity potential chosen is Prox.81 proposed by Blocki et al.in 1981.Furthermore,we apply this model to predict the half-lives of possible 2p radioactive candidates whose 2p radioactivity is energetically allowed or observed but not yet quantified in the evaluated nuclear properties table NUBASE2016.The predicted results are in good agreement with those from other theoretical models and empirical formulas,namely the effective liquid drop model(ELDM),generalized liquid drop model(GLDM),Gamow-like model,Sreeja formula and Liu formula.
基金the National Key Research and Development Program(MOST 2022YFA1602303 and MOST 2023YFA1606404)the National Natural Science Foundation of China(Nos.12347106,2147101,11925502,11935001 and 11961141003)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB34030000).
文摘The recently discovered,extremely proton-rich nuclide 18 Mg exhibits ground-state decay via two sequential two-proton(2p)emissions through the intermediate nucleus,16Ne.This study investigates the structure and the initial 2p decay mechanism of^(18)Mgby examining the density and correlations of the valence protons using a three-body Gamow coupled-channel method.The results show that the ground state of^(18)Mgis significantly influenced by the continuum,resulting in a significant s-wave component.However,based on the current framework,this does not lead to a significant deviation in mirror symmetry in either the structure or spectroscopy of the 18Mg-18C pair.Additionally,the time evolution analysis of the^(18)Mgground state suggests a simultaneous 2p emission during the first step of decay.The observed nucleon-nucleon correlations align with those of the light-mass 2p emitters,indicating a consistent decay behavior within this nuclear region.
