We systematically studied the evaporation residue cross sections of ^(48)Ca-induced reactions on lanthanide and actinide target nuclei under the Dinuclear System(DNS)model framework to check the reliability and applic...We systematically studied the evaporation residue cross sections of ^(48)Ca-induced reactions on lanthanide and actinide target nuclei under the Dinuclear System(DNS)model framework to check the reliability and applicability of the model.To produce new proton-rich Fl and Lv isotopes through hot fusion reactions in the superheavy element region with Z≥104,we utilized the reactions ^(48)Ca+^(236,238,239) Pu and ^(48)Ca+^(242,243,244,250) Cm.However,owing to the detection limit of available equipment(0.1 pb),only 283Fl and 287−289Lv,which have the maximum evaporation residue cross section values of 0.149,0.130,9.522,and 0.309 pb,respectively,can be produced.Furthermore,to produce neutron-deficient isotopes of actinides near the proton drip line with Z=93−100,we attempted to generate the new isotopes(224−227Pu,228−232,237Cm)using the reactions ^(48)Ca+180,182,183 W and ^(48)Ca+^(184,186,187,192) Os.The maximum evaporation residue cross section values are 0.07,0.06,0.26,and 0.30 nb for the former set of reactions,and 1.96 pb,5.73 pb,12.16 pb,19.39 pb,54.79 pb,and 6.45 nb for the latter,respectively.These results are expected to provide new information for the future synthesis of unknown neutron-deficient isotopes.展开更多
The experimental data of the isotopic distribution for projectile-like fragments are presented for the 17,18N + 197Au reaction at 33 MeV/u. The width of the isotopic distributions for lSN projectile is significantly ...The experimental data of the isotopic distribution for projectile-like fragments are presented for the 17,18N + 197Au reaction at 33 MeV/u. The width of the isotopic distributions for lSN projectile is significantly broader than that for 17N projectile, and the average N/Z ratio of the former shifts to higher neutron number side. As long as the realistic nucleon density distribution is used, the isotopic distribution for fragments is reproduced by the simple abrasion-ablation model calculation, which thus provides an independent way to determine the surface distribution of the nuclear matter density for neutron-rich nuclei.展开更多
Nuclei in the light actinide region with Z 92,N 134 are predicted to be candidates for shape coexistence[1],some nuclei in this region are also predicted to have stable octupole deformation[2]. Actinide nuclei with...Nuclei in the light actinide region with Z 92,N 134 are predicted to be candidates for shape coexistence[1],some nuclei in this region are also predicted to have stable octupole deformation[2]. Actinide nuclei with N=134have been produced up to plutonium (228Pu), and the lightest plutonium isotope and neptunium isotope discoveredso far are 228Pu and 225Np respectively. A campaign has been started to investigate the nuclei in this region. Thereaction 20Ne + 209Bi was used to produce 224Np (N=131) in fusion-evaporation reaction as the first step.展开更多
Many isotopes of Np,Pu,Am,and Cm around the N=126 shell still have not been produced in the laboratory.This study aims to investigate the cross sections and yields of the neutron-deficient nuclei of Np,Pu,Am,and Cm pr...Many isotopes of Np,Pu,Am,and Cm around the N=126 shell still have not been produced in the laboratory.This study aims to investigate the cross sections and yields of the neutron-deficient nuclei of Np,Pu,Am,and Cm produced in the proton-induced spallations of transuranium elements.The isospin-dependent quantum molecular dynamics(IQMD)model is applied to study the dynamical process of reaction,and the subsequent decay process is simulated by the GEMINI++model.The IQMD-GEMINI++model is applied to calculate the cross section,kinetic energy,and angular distribution of the isotopic productions around N=126.The Lindhand,Scharff,and Schiott theory is applied to calculate the energy loss of different heavy nuclei in the target material.A comparison between the data and the calculations shows that the IQMD-GEMINI++model can reproduce the production cross sections of the neutron-deficient nuclei in spallation within approximately 1.5 orders of magnitude.The maximum cross section of the undiscovered isotopes of Np,Pu,Am,and Cm is about 10-5 mb,while the kinetic energies of the productions are all less than 16 MeV.The angular distribution shows that the emission direction of production is mostly at a backward angle.The range of production in the target is within the range of 10-7to 10-5cm.This range is the effective target thickness for the online identification of undiscovered isotopes.Based on the effective thickness of the target and assuming an intensity of 120μA for the proton beam,the yields of the undiscovered neutron-deficient nuclei are calculated.Productions of the undiscovered isotopes of Np,Pu,Am,and Cm by the proton-induced spallations of transuranium elements are feasible.However,experimental techniques for online identification of neutron-deficient nuclei produced in proton-induced spallation should be developed.展开更多
A method is proposed to determine the one-neutron Sn or two-neutron S2n separation energy of neutron- rich isotopes. Relationships between Sn (S2n) and isotopic cross sections have been deduced from an empirical for...A method is proposed to determine the one-neutron Sn or two-neutron S2n separation energy of neutron- rich isotopes. Relationships between Sn (S2n) and isotopic cross sections have been deduced from an empirical formula, i.e., the cross section of an isotope exponentially depends on the average binding energy per nucleon B/A. The proposed relationships have been verified using the neutron-rich copper isotopes measured in the 64A MeV S6Kr 9Be reaction. Sn, S2n, and B/A for the very neutron-rich 77,78,79Cu isotopes are determined from the proposed correlations. It is also proposed that the correlations between Sn, S2n and isotopic cross sections can be used to find the location of neutron drip line isotopes.展开更多
Excited states in low-energy spectra of ^(70-76) Ni are considered. Accordingly, pairing forces in the form of surface delta interaction are employed to account for the formation of the ground state multiplet with sen...Excited states in low-energy spectra of ^(70-76) Ni are considered. Accordingly, pairing forces in the form of surface delta interaction are employed to account for the formation of the ground state multiplet with seniority v= 2 states. The multiplet splitting is described with mass relationships of masses of neighboring nuclei. Subsequently, the seniority model is adopted to reproduce or predict the states v= 3 in odd-even isotopes and v= 4 in even-even isotopes. The correct account of the 2^(+)_(1) state should allow for the description of the reversed order of J = 4 states with v= 2 and v= 4 observed in experiments. The results obtained are compared with the structure of similar multiplets in N=50 isotones.展开更多
The structure of neutron-rich Ca isotopes is studied in the spherical Skyrme-Hartree-Fock-Bogoliubov(SHFB)approach with SLy5,SLy5+T,and 36 sets of TIJ parametrizations.The calculated results are compared with the avai...The structure of neutron-rich Ca isotopes is studied in the spherical Skyrme-Hartree-Fock-Bogoliubov(SHFB)approach with SLy5,SLy5+T,and 36 sets of TIJ parametrizations.The calculated results are compared with the available experimental data for the average binding energies,two-neutron separation energies and charge radii.It is found that the SLy5+T,T31,and T32 parametrizations reproduce best the experimental properties,especially the neutron shell effects at N=20,28 and 32,and the recently measured two-neutron separation energy of 56Ca.The calculations with the SLy5+T and T31 parametrizations are extended to isotopes near the neutron drip line.The neutron giant halo structure in the very neutron-rich Ca isotopes is not seen with these two interactions.However,depleted neutron central densities are found in these nuclei.By analyzing the neutron mean-potential,the reason for the bubble-like structure formation is given.展开更多
The ground-state deformations and B(E2) values of Ne and Mg nuclei around N = 20 are studied within the framework of the macroscopic-microscopic (MM) model with isospin-dependent Nilsson potential. The calculated ...The ground-state deformations and B(E2) values of Ne and Mg nuclei around N = 20 are studied within the framework of the macroscopic-microscopic (MM) model with isospin-dependent Nilsson potential. The calculated results are compared with those obtained from standard Nilsson parameters and with experimental ones. It is found that the calculations with new Nilsson parameters well reproduce the experimental large deformations and B(E2) values for Ne and Mg nuclei around N = 20. The N = 20 shell closure of Ne and Mg isotopes disappears in the MM model and this agrees with experimental data.展开更多
The ratio of pairing-energy coefficient to temperature (ap/T) of neutron-rich fragments produced in spallation reactions has been investigated by adopting an isobaric yield ratio method deduced in the framework of a...The ratio of pairing-energy coefficient to temperature (ap/T) of neutron-rich fragments produced in spallation reactions has been investigated by adopting an isobaric yield ratio method deduced in the framework of a modified Fisher model. A series of spallation reactions, 0.5A and 1A GeV 208Pb + p, 1A GeV 238U + p, 0.5A GeV 136Xe + d, 0.2A, 0.5A and 1A GeV 136Xe + p, and 56Fe + p with incident energy ranging from 0.3A to 1.5A GeV, has been analysed. An obvious odd-even staggering is shown in the fragments with small neutron excess (I=N-Z), and in the relatively small-A fragments which have large I. The values of ap/T for the fragments, with I from 0 to 36, have been found to be in a range from -4 to 4, and most values of ap/T fall in the range from -1 to 1. It is suggested that a small pairing-energy coefficient should be considered in predicting the cross sections of fragments in spallation reactions. It is also concluded that the method proposed in this article is not good for fragments with A/As〉 85% (where As is the mass number of the spallation system).展开更多
The elemental fragmentation cross sections of boron fragments produced by stable and neutron-rich^(12-16)C beams with a carbon target were systematically measured at an incident beam energy of approximately 240 MeV/nu...The elemental fragmentation cross sections of boron fragments produced by stable and neutron-rich^(12-16)C beams with a carbon target were systematically measured at an incident beam energy of approximately 240 MeV/nucleon.The measured cross sections were found to increase as the projectile mass number increases.The observed feature is explained qualitatively based on the abrasion-ablation two-stage reaction model and is compared quantitatively with predictions from various reaction models,including empirical and statistical models.All models agree with the measured cross sections within a factor of 2.展开更多
The properties of neutron-rich boron isotopes are studied in the relativistic continuum Hartree-Bogoliubov theory in coordinate space with NL-SH,PK1 and TM2 effective interactions.Pairing corrections are taken into ac...The properties of neutron-rich boron isotopes are studied in the relativistic continuum Hartree-Bogoliubov theory in coordinate space with NL-SH,PK1 and TM2 effective interactions.Pairing corrections are taken into account by a density dependent force of zero range.The binding energies calculated for these nuclei agree with the experimental data quite well.The neutron-rich nucleus 17 B has been predicted to have a two-neutron halo structure in its ground state.The halo structure of 17 B is reproduced in a self-consistent way,and this halo is shown to be formed by the valence neutron level 2s 1/2.展开更多
基金National Natural Science Foundation of China(Nos.12175064 and U2167203)Hunan Outstanding Youth Science Foundation(No.2022JJ10031).
文摘We systematically studied the evaporation residue cross sections of ^(48)Ca-induced reactions on lanthanide and actinide target nuclei under the Dinuclear System(DNS)model framework to check the reliability and applicability of the model.To produce new proton-rich Fl and Lv isotopes through hot fusion reactions in the superheavy element region with Z≥104,we utilized the reactions ^(48)Ca+^(236,238,239) Pu and ^(48)Ca+^(242,243,244,250) Cm.However,owing to the detection limit of available equipment(0.1 pb),only 283Fl and 287−289Lv,which have the maximum evaporation residue cross section values of 0.149,0.130,9.522,and 0.309 pb,respectively,can be produced.Furthermore,to produce neutron-deficient isotopes of actinides near the proton drip line with Z=93−100,we attempted to generate the new isotopes(224−227Pu,228−232,237Cm)using the reactions ^(48)Ca+180,182,183 W and ^(48)Ca+^(184,186,187,192) Os.The maximum evaporation residue cross section values are 0.07,0.06,0.26,and 0.30 nb for the former set of reactions,and 1.96 pb,5.73 pb,12.16 pb,19.39 pb,54.79 pb,and 6.45 nb for the latter,respectively.These results are expected to provide new information for the future synthesis of unknown neutron-deficient isotopes.
基金supported by National Natural Science Foundation of China (Nos. 11035001, 11175003, 10875002, 10775005)
文摘The experimental data of the isotopic distribution for projectile-like fragments are presented for the 17,18N + 197Au reaction at 33 MeV/u. The width of the isotopic distributions for lSN projectile is significantly broader than that for 17N projectile, and the average N/Z ratio of the former shifts to higher neutron number side. As long as the realistic nucleon density distribution is used, the isotopic distribution for fragments is reproduced by the simple abrasion-ablation model calculation, which thus provides an independent way to determine the surface distribution of the nuclear matter density for neutron-rich nuclei.
文摘Nuclei in the light actinide region with Z 92,N 134 are predicted to be candidates for shape coexistence[1],some nuclei in this region are also predicted to have stable octupole deformation[2]. Actinide nuclei with N=134have been produced up to plutonium (228Pu), and the lightest plutonium isotope and neptunium isotope discoveredso far are 228Pu and 225Np respectively. A campaign has been started to investigate the nuclei in this region. Thereaction 20Ne + 209Bi was used to produce 224Np (N=131) in fusion-evaporation reaction as the first step.
基金Supported by the Open Project of Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology(NLK2020-02)the National Natural Science Foundation of China(11875328,12075327)the Fundamental Research Funds for the Central Universities,Sun Yat-Sen University(22qntd1801)。
文摘Many isotopes of Np,Pu,Am,and Cm around the N=126 shell still have not been produced in the laboratory.This study aims to investigate the cross sections and yields of the neutron-deficient nuclei of Np,Pu,Am,and Cm produced in the proton-induced spallations of transuranium elements.The isospin-dependent quantum molecular dynamics(IQMD)model is applied to study the dynamical process of reaction,and the subsequent decay process is simulated by the GEMINI++model.The IQMD-GEMINI++model is applied to calculate the cross section,kinetic energy,and angular distribution of the isotopic productions around N=126.The Lindhand,Scharff,and Schiott theory is applied to calculate the energy loss of different heavy nuclei in the target material.A comparison between the data and the calculations shows that the IQMD-GEMINI++model can reproduce the production cross sections of the neutron-deficient nuclei in spallation within approximately 1.5 orders of magnitude.The maximum cross section of the undiscovered isotopes of Np,Pu,Am,and Cm is about 10-5 mb,while the kinetic energies of the productions are all less than 16 MeV.The angular distribution shows that the emission direction of production is mostly at a backward angle.The range of production in the target is within the range of 10-7to 10-5cm.This range is the effective target thickness for the online identification of undiscovered isotopes.Based on the effective thickness of the target and assuming an intensity of 120μA for the proton beam,the yields of the undiscovered neutron-deficient nuclei are calculated.Productions of the undiscovered isotopes of Np,Pu,Am,and Cm by the proton-induced spallations of transuranium elements are feasible.However,experimental techniques for online identification of neutron-deficient nuclei produced in proton-induced spallation should be developed.
基金Supported by Program for Science and Technology Innovation Talents at Universities of Henan Province(13HASTIT046)Natural and Science Foundation in Henan Province(162300410179)+1 种基金Program for the Excellent Youth at Henan Normal University(154100510007)the support from the Creative Experimental Project of National Undergraduate Students(CEPNU 201510476017)
文摘A method is proposed to determine the one-neutron Sn or two-neutron S2n separation energy of neutron- rich isotopes. Relationships between Sn (S2n) and isotopic cross sections have been deduced from an empirical formula, i.e., the cross section of an isotope exponentially depends on the average binding energy per nucleon B/A. The proposed relationships have been verified using the neutron-rich copper isotopes measured in the 64A MeV S6Kr 9Be reaction. Sn, S2n, and B/A for the very neutron-rich 77,78,79Cu isotopes are determined from the proposed correlations. It is also proposed that the correlations between Sn, S2n and isotopic cross sections can be used to find the location of neutron drip line isotopes.
基金Supported by the Interdisciplinary Scientific and Educational School of Moscow University"Fundamental and Applied Space Research"
文摘Excited states in low-energy spectra of ^(70-76) Ni are considered. Accordingly, pairing forces in the form of surface delta interaction are employed to account for the formation of the ground state multiplet with seniority v= 2 states. The multiplet splitting is described with mass relationships of masses of neighboring nuclei. Subsequently, the seniority model is adopted to reproduce or predict the states v= 3 in odd-even isotopes and v= 4 in even-even isotopes. The correct account of the 2^(+)_(1) state should allow for the description of the reversed order of J = 4 states with v= 2 and v= 4 observed in experiments. The results obtained are compared with the structure of similar multiplets in N=50 isotones.
基金Supported by the National Natural Science Foundation of China(U1832120,11675265)the State Scholarship Fund of China Scholarship Council(201708130035)the Natural Science Foundation for Outstanding Young Scholars of Hebei Province of China(A2018210146)
文摘The structure of neutron-rich Ca isotopes is studied in the spherical Skyrme-Hartree-Fock-Bogoliubov(SHFB)approach with SLy5,SLy5+T,and 36 sets of TIJ parametrizations.The calculated results are compared with the available experimental data for the average binding energies,two-neutron separation energies and charge radii.It is found that the SLy5+T,T31,and T32 parametrizations reproduce best the experimental properties,especially the neutron shell effects at N=20,28 and 32,and the recently measured two-neutron separation energy of 56Ca.The calculations with the SLy5+T and T31 parametrizations are extended to isotopes near the neutron drip line.The neutron giant halo structure in the very neutron-rich Ca isotopes is not seen with these two interactions.However,depleted neutron central densities are found in these nuclei.By analyzing the neutron mean-potential,the reason for the bubble-like structure formation is given.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10125521 and 10535010, the National Major State Basic Research and Development Programme of China under Grant No G2000077400, the Knowledge Innovation Project of Chinese Academy of Sciences under Grant No KJCX2-SW-N02, and the Fund of Education Ministry of China under Grant No 20010284036.
文摘The ground-state deformations and B(E2) values of Ne and Mg nuclei around N = 20 are studied within the framework of the macroscopic-microscopic (MM) model with isospin-dependent Nilsson potential. The calculated results are compared with those obtained from standard Nilsson parameters and with experimental ones. It is found that the calculations with new Nilsson parameters well reproduce the experimental large deformations and B(E2) values for Ne and Mg nuclei around N = 20. The N = 20 shell closure of Ne and Mg isotopes disappears in the MM model and this agrees with experimental data.
基金Supported by National Natural Science Foundation of China(U1732135)Natural Science Foundation of Henan Province(162300410179)Henan Normal University for the Excellent Youth(154100510007)
文摘The ratio of pairing-energy coefficient to temperature (ap/T) of neutron-rich fragments produced in spallation reactions has been investigated by adopting an isobaric yield ratio method deduced in the framework of a modified Fisher model. A series of spallation reactions, 0.5A and 1A GeV 208Pb + p, 1A GeV 238U + p, 0.5A GeV 136Xe + d, 0.2A, 0.5A and 1A GeV 136Xe + p, and 56Fe + p with incident energy ranging from 0.3A to 1.5A GeV, has been analysed. An obvious odd-even staggering is shown in the fragments with small neutron excess (I=N-Z), and in the relatively small-A fragments which have large I. The values of ap/T for the fragments, with I from 0 to 36, have been found to be in a range from -4 to 4, and most values of ap/T fall in the range from -1 to 1. It is suggested that a small pairing-energy coefficient should be considered in predicting the cross sections of fragments in spallation reactions. It is also concluded that the method proposed in this article is not good for fragments with A/As〉 85% (where As is the mass number of the spallation system).
基金Supported by the National Natural Science Foundation of China(U1732134,U1832205)the Heavy Ion Research Facility in Lanzhou(HIRFL)the open research project of CAS large research infrastructures。
文摘The elemental fragmentation cross sections of boron fragments produced by stable and neutron-rich^(12-16)C beams with a carbon target were systematically measured at an incident beam energy of approximately 240 MeV/nucleon.The measured cross sections were found to increase as the projectile mass number increases.The observed feature is explained qualitatively based on the abrasion-ablation two-stage reaction model and is compared quantitatively with predictions from various reaction models,including empirical and statistical models.All models agree with the measured cross sections within a factor of 2.
基金Supported by National Natural Science Foundation of China (11075133,10205019,11075190)Fundamental Research Funds for the Central Universities (XDJK2010D005,XDJK2010C049)+1 种基金Knowledge Innovation Program of Chinese Academy of Sciences(KJCX2-YW-N44)Open Research Program at Large Scale Facility of Chinese Academy of Sciences (O903010YKF)
文摘The properties of neutron-rich boron isotopes are studied in the relativistic continuum Hartree-Bogoliubov theory in coordinate space with NL-SH,PK1 and TM2 effective interactions.Pairing corrections are taken into account by a density dependent force of zero range.The binding energies calculated for these nuclei agree with the experimental data quite well.The neutron-rich nucleus 17 B has been predicted to have a two-neutron halo structure in its ground state.The halo structure of 17 B is reproduced in a self-consistent way,and this halo is shown to be formed by the valence neutron level 2s 1/2.