In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion-ablation model and the isoscaling behaviour of projectile-like fragmen...In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion-ablation model and the isoscaling behaviour of projectile-like fragments has been discussed. The isoscaling parameters α and β have been extracted respectively, for hot fragments before evaporation and cold fragments after evaporation. It looks that the evaporation has stronger effect on α than β. For cold fragments, a monotonic increase of α and ｜β｜ with the increase of Z and N is observed. The relation between isoscaling parameter and the change of isospin content is discussed.展开更多
Traditionally,isoscaling has been interpreted and applied within the framework of the grand canonical ensemble,based on the assumption that fragment production occurs following the attainment of a statistical equilibr...Traditionally,isoscaling has been interpreted and applied within the framework of the grand canonical ensemble,based on the assumption that fragment production occurs following the attainment of a statistical equilibrium state.However,the influence of the symmetry energy can lead to differences in the neutron and density distribution in neutron-rich nuclei.This in turn may impact the iso scaling parameters(usually denoted byαandβ).We examine the isoscaling properties for neutron-rich fragments produced in highly asymmetric systems on inverse kinematics,namely^(40,48)Ca and ^(58,64)Ni+^(9)Be at 140 MeV per nucleon.We evaluate α and β values and sort them as a function of the neutron excess I≡N-Z.The significant differences in a extracted from fragments within different ranges of I emphasize the importance of understanding the dependence of isoscaling parameters on fragments generated in various collision regions.Furthermore,the|β(N)|/α(Z)value for a specific fragment in small size and highly iso spin asymmetry systems can serve as a probe to detect the variations in neutron density and proton density in different regions of the nucleus and indicate the limitations of theoretical models in investigating these issues.展开更多
The isoscaling parameters aevai in the fissioning systems,i.e.,those extracted from the Evaluated Nuclear Data Library(ENDF/B-VIII.O)and the Joint Evaluated Fission and Fusion File(JEFF-3.3),show an obvious difference...The isoscaling parameters aevai in the fissioning systems,i.e.,those extracted from the Evaluated Nuclear Data Library(ENDF/B-VIII.O)and the Joint Evaluated Fission and Fusion File(JEFF-3.3),show an obvious difference from simple statistic model prediction where only the symmetry energy plays the dominant role.To explain the aeVai as a function of the charge number of the fission fragment,a statistic scission point model is adopted.Our analysis shows that the effects of the shell correction,nuclear shape deformation,and intrinsic temperature of fission fragments are indispensable as well as the symmetry energy.Furthermore,an alternative method for extracting the intrinsic temperatures of fission fragments is proposed based on the isoscaling relationship in fission fragments.The intrinsic temperatures of the light fragments are higher than those of the heavy fragments.展开更多
An isoratio method is proposed to study the chemical potential of neutrons(protons) from the yield ratio of isotopes(isotones) differing in neutron-excess(I = N- Z). The measured fragments in the 140 A MeV ^(40),^(48)...An isoratio method is proposed to study the chemical potential of neutrons(protons) from the yield ratio of isotopes(isotones) differing in neutron-excess(I = N- Z). The measured fragments in the 140 A MeV ^(40),^(48) Ca and^(58),^(64) Ni +~9Be reactions, as well as those in the simulated^(58),^(64) Ni +~9Be reactions by using the antisymmetric molecular dynamics(AMD) model plus the secondary decay model gemini, have been adopted to perform the isoratio analysis.The results of the isoratio method verify that they are similar to that of the well known isoscaling method. The isoratio scaling phenomenon suggested by the isoratio method has also been found in the measured data and the fragments simulated by the AMD + gemini models.展开更多
This paper summarizes the isoscaling and isospin related studies in asymmetry nuclear reactions by different dynamic and sta tistical models. Isospin dependent quantum molecular dynamics model (IQMD) and lattice gas m...This paper summarizes the isoscaling and isospin related studies in asymmetry nuclear reactions by different dynamic and sta tistical models. Isospin dependent quantum molecular dynamics model (IQMD) and lattice gas model (LGM) are used to study the isoscaling properties and isoscaling parameters dependence on incident energies, impact parameters, temperature and other parameters. In the LGM model, the signal of phase transition has been found in free neutron (proton) chemical potential dif ference Δμn or Δμp as a function of temperature, or in free neutron and proton chemical potential difference Δμn-Δμp. Density dependence of symmetry energy coefficient Csym(ρ/ρ0) is also studied in the frame of LGM, with the potential parameters which can reproduce the nuclear ground state property, soft density dependence of symmetry energy is deduced from the sim ulation results. Giant dipole resonance (GDR) induced by isospin asymmetry in entrance channel is also studied via IQMD model, and the dynamic dipole resonance shows isospin sensitivity on the isospin asymmetry of entrance channel and sym metry energy of the nuclear equation of state (EOS). GDR can also be regarded as a possible isospin sensitive signature.展开更多
基金Project supported in part by the Shanghai Development Foundation for Science and Technology of China （Crant Nos 05XD14021 and 03QA14066）, the National Natural Science Foundation of China （Grant Nos 10328259, 10135030, 10405032, 10405033 and 10475108）, the Major State Basic Research Development Program of China （Contract No G200077404）.
文摘In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion-ablation model and the isoscaling behaviour of projectile-like fragments has been discussed. The isoscaling parameters α and β have been extracted respectively, for hot fragments before evaporation and cold fragments after evaporation. It looks that the evaporation has stronger effect on α than β. For cold fragments, a monotonic increase of α and ｜β｜ with the increase of Z and N is observed. The relation between isoscaling parameter and the change of isospin content is discussed.
基金Supported by the National Natural Science Foundation of China(12375123,11975091)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province(21IRTSTHN011),China。
文摘Traditionally,isoscaling has been interpreted and applied within the framework of the grand canonical ensemble,based on the assumption that fragment production occurs following the attainment of a statistical equilibrium state.However,the influence of the symmetry energy can lead to differences in the neutron and density distribution in neutron-rich nuclei.This in turn may impact the iso scaling parameters(usually denoted byαandβ).We examine the isoscaling properties for neutron-rich fragments produced in highly asymmetric systems on inverse kinematics,namely^(40,48)Ca and ^(58,64)Ni+^(9)Be at 140 MeV per nucleon.We evaluate α and β values and sort them as a function of the neutron excess I≡N-Z.The significant differences in a extracted from fragments within different ranges of I emphasize the importance of understanding the dependence of isoscaling parameters on fragments generated in various collision regions.Furthermore,the|β(N)|/α(Z)value for a specific fragment in small size and highly iso spin asymmetry systems can serve as a probe to detect the variations in neutron density and proton density in different regions of the nucleus and indicate the limitations of theoretical models in investigating these issues.
基金Supported by the National Natural Science Foundation of China(11790325,11875323,11875125,11947410,11705163,11790320,11790323,11961141003)the National Key R&D Program of China(2018 YFA0404404)+1 种基金the Continuous Basic Scientific Research Project(WDJC-2019-09,WDJC-2019-13,BJ20002501)of the funding of China Institute of Atomic EnergyChinese-Polish Joint project by the National Science Foundation of China(11961131010)。
文摘The isoscaling parameters aevai in the fissioning systems,i.e.,those extracted from the Evaluated Nuclear Data Library(ENDF/B-VIII.O)and the Joint Evaluated Fission and Fusion File(JEFF-3.3),show an obvious difference from simple statistic model prediction where only the symmetry energy plays the dominant role.To explain the aeVai as a function of the charge number of the fission fragment,a statistic scission point model is adopted.Our analysis shows that the effects of the shell correction,nuclear shape deformation,and intrinsic temperature of fission fragments are indispensable as well as the symmetry energy.Furthermore,an alternative method for extracting the intrinsic temperatures of fission fragments is proposed based on the isoscaling relationship in fission fragments.The intrinsic temperatures of the light fragments are higher than those of the heavy fragments.
基金Supported by the Program for Science and Technology Innovation Talents in Universities of Henan Province under Grant No.13HASTIT046
文摘An isoratio method is proposed to study the chemical potential of neutrons(protons) from the yield ratio of isotopes(isotones) differing in neutron-excess(I = N- Z). The measured fragments in the 140 A MeV ^(40),^(48) Ca and^(58),^(64) Ni +~9Be reactions, as well as those in the simulated^(58),^(64) Ni +~9Be reactions by using the antisymmetric molecular dynamics(AMD) model plus the secondary decay model gemini, have been adopted to perform the isoratio analysis.The results of the isoratio method verify that they are similar to that of the well known isoscaling method. The isoratio scaling phenomenon suggested by the isoratio method has also been found in the measured data and the fragments simulated by the AMD + gemini models.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10875160, 10979074 and 11035009)the Major State Basic Research Development Program in China (Grant No. 2007CB815004)
文摘This paper summarizes the isoscaling and isospin related studies in asymmetry nuclear reactions by different dynamic and sta tistical models. Isospin dependent quantum molecular dynamics model (IQMD) and lattice gas model (LGM) are used to study the isoscaling properties and isoscaling parameters dependence on incident energies, impact parameters, temperature and other parameters. In the LGM model, the signal of phase transition has been found in free neutron (proton) chemical potential dif ference Δμn or Δμp as a function of temperature, or in free neutron and proton chemical potential difference Δμn-Δμp. Density dependence of symmetry energy coefficient Csym(ρ/ρ0) is also studied in the frame of LGM, with the potential parameters which can reproduce the nuclear ground state property, soft density dependence of symmetry energy is deduced from the sim ulation results. Giant dipole resonance (GDR) induced by isospin asymmetry in entrance channel is also studied via IQMD model, and the dynamic dipole resonance shows isospin sensitivity on the isospin asymmetry of entrance channel and sym metry energy of the nuclear equation of state (EOS). GDR can also be regarded as a possible isospin sensitive signature.
