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The α-target semimicroscopic single folding potentials have been derived by folding a composite (repul-sive and attractive) effective α-α interaction with the α-cluster distribution density in the target nuclei. The obtained potentials are considered as the real part of the nuclear optical model potentials, while the imaginary parts are phe-nomenologicaly expressed using the Woods-Saxon form. Nine sets of measured experimental data of the 4He+12C and 4 He+16O elastic rainbow scattering over the energy range 80-240 MeV are analyzed using the obtained potentials. The data are successfully reproduced using the extracted potentials. The resulted reaction cross sections are also investigated and compared with the available corresponding data. 相似文献
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《中国科学:物理学 力学 天文学(英文版)》2019,(12)
The entrance-channel dynamics including capture, fusion, and quasifission processes for the reaction ~(40)Ca+~(208)Pb is investigated in the fully microscopic time-dependent Hartree-Fock(TDHF) theory. The calculations are performed in three-dimensional Cartesian coordinate without any symmetry restrictions, in which the full Skyrme energy functional SLy4d and SLy5 are adopted.We study the energy dependence of capture cross sections, and find that the experimental data are well reproduced by the TDHF calculations. Both fusion and quasifission events are observed in the reaction ~(40)Ca+~(208)Pb. The contact time, mass and charge of quasifission fragments show a wide distribution in SLy4d compared with SLy5, implying that more nucleons are transferred in the SLy4d calculations. We find that the total kinetic energy of quasifission fragments in the TDHF calculations is distributed around Viola systematics, indicating that most of the relative kinetic energy is dissipated in quasifission dynamics. 相似文献
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Within the framework of the isospin-dependent quantum molecular dynamics model, along with the GEMINI model, the ~(86)Kr+~(181)Ta reaction at 80, 120 and 160 MeV/nucleon and the ~(78)Kr+~(181)Ta reaction at 160 MeV/nucleon are studied, and the production cross sections of the generated fragments are calculated. More intermediate and large mass fragments can be produced in the reactions with a large range of impact parameter. The production cross sections of nuclei such as the isotopes of Si and P generally decrease with increasing incident energy.Isotopes near the neutron drip line are produced more in the neutron-rich system ~(86)Kr+~(181)Ta. 相似文献
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One of the important reactions for nucleosynthesis in the carbon burning phase in high-mass stars is the ~(12)C+~(12)C fusion reaction. In this study, we investigate the influences of the nuclear potentials and screening effect on astrophysically interesting ~(12)C+~(12)C fusion reaction observables at sub-barrier energies by using the microscopic α-αdouble folding cluster(DFC) potential and the proximity potential. In order to model the screening effects on the experimental data, a more general exponential cosine screened Coulomb(MGECSC) potential including Debye and quantum plasma cases has been considered in the calculations for the ~(12)C+~(12)C fusion reaction. In the calculations of the reaction observables, the semi-classical Wentzel-Kramers-Brillouin(WKB) approach and coupled channel(CC)formalism have been used. Moreover, in order to investigate how the potentials between ~(12)C nuclei produce molecular cluster states of ~(24)Mg, the normalized resonant energy states of ~(24)Mg cluster bands have been calculated for the DFC potential. By analyzing the results produced from the fusion of ~(12)C+~(12)C, it is found that taking into account the screening effects in terms of MGECSC is important for explaining the ~(12)C+~(12)C fusion data, and the microscopic DFC potential is better than the proximity potential in explaining the experimental data, also considering that clustering is dominant for the structure of the ~(24)Mg nucleus. 相似文献
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《中国科学:物理学 力学 天文学(英文版)》2017,(9)
The quasifission dynamics in the reaction ~(48)Ca+~(244)Pu is investigated in the framework of time-dependent Hartree-Fock(TDHF)theory. The calculations are performed in three-dimensional Cartesian coordinate without any symmetry restrictions. The full Skyrme energy functional is incorporated in our TDHF implementation. The quasifission dynamics is quite sensitive to the angular momentum of colliding system. The contact time of quasifission decreases as a function of angular momentum and then forms a plateau with small oscillations. The quasifission process is accompanied by an important multi-nucleon transfer. The quantum shell effect plays a crucial role in the mass and charge of quasifission fragments. The mass-angle distribution of the fragments is calculated, which can be compared directly with future experiments. 相似文献
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25MeV/u 40)Ar+209Bi裂变反应研究 总被引:1,自引:0,他引:1
实验对25MeV/u 40Ar+209Bi体系的裂变反应,利用线性动量转移的分窗选择不同的激发能,研究裂变动能分布和质量分布与热核初始激发能的关系.实验证实激发能小于380MeV时裂变总动能分布与低激发能复合核相似.激发能大于380MeV时,最可几动能呈现出随激发增加而增加,并出现高能非对称性,而且质量分布宽度随激发能增加而迅速增大. 相似文献
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30MeV/u 40Ar+58,64Ni、115In反应中IMF的元素分布 总被引:1,自引:1,他引:0
在5°—140°范围内测量了30MeV/u40Ar束流轰击不同靶核(58Ni、64Ni、115In)时出射的中等质量碎片的元素分布.在20°—80°之间,观察到了原子序数大于弹核原子库数的出射碎片(Z=3—24),发现中等质量碎片的微分截面在其原子库数从小于弹核原子库数向大于弹核原子库数变化过程中是连续变化的,该角区出就碎片的元素分布与弹核原子库数关系不大.对中能区核反应的过渡性质做了讨论,指出了探测阈对所测得的元素分布的影响,并讨论了元素分布的幂指数规律. 相似文献
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Secular Motion Frequencies of ~9Be~+ Ions and ~(40)Ca~+ Ions in Bi-component Coulomb Crystals
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We obtain bi-component Coulomb crystals using laser-cooled ~(40)Ca~+ ions to sympathetically cool ~9Be~+ ions in a linear Paul trap. The shell structures of the bi-component Coulomb crystals are investigated. The secular motion frequencies of the two different ions are determined and compared with those in the single-component Coulomb crystals. In the radial direction, the resonant motion frequencies of the two ionic species shift toward each other due to the strong motion coupling in the ion trap. In the axial direction, the motion frequency of the laser-cooled~(40)Ca~+is impervious to the sympathetically cooled ~9Be~+ ions because the spatially separation of the two different ionic species leads to the weak motion coupling in the axial direction. 相似文献
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The pre-scission neutrons measured in the reactions 16O 181Ta and 19F 178Hf are studied via a Langevin equation coupled with a statistical decay model. We find that because of the mass asymmetry of different entrance channels, the spin distributions of compound nuclei would be different, consequently, the measured neutrons in these two reactions would also different. This means that the entrance channel will affect the particle emission in the fission process of hot nuclei. 相似文献
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30MeV/u 40Ar+58,64Ni和115In反应中中等质量碎片的角分布 总被引:1,自引:1,他引:0
在5°—140°范围内测量了30MeV/u 40Ar束流轰击不同靶核(58Ni、64Ni、115In)后出射的中等质量碎片(IMF,Z=3—19)的角分布.用指数分布函数dσ/dΩ=N·exp(–θ/α)对出射碎片角分布分角区做了拟合.对3个反应系统分别提取出与相互作用时间有关的衰减因子α和与发射源强度有关的物理量N,讨论了α与N在不同角区与反应系统和出射IMF电荷数的关系.考察了角分布与同位旋自由度和反应系统对称性的关系. 相似文献
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Angular distribution measurement for ~(12)C fragmentation via ~(12)C + ~(12)C scattering at 100 MeV/u
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The angular distributions and energy spectra of~(11)B,~(10)B,and~9Be fragments of~(12)C in the angular range from 1.0°~to 7.5°~at 100 Me V/u were obtained via~(12)C+~(12)C scattering.Detailed comparisons are presented between the experimental data and the modified antisymmetrized molecular dynamics(AMD-FM),binary intranuclear cascade model(BIC)and Liege intranuclear cascade model(INCL++).The experimental angular distributions and energy spectra are well reproduced by the AMD-FM calculations but fail to be reproduced by the physical models installed in the Geant4 program,including the BIC and INCL++models. 相似文献
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HE Jian-jun S.Kubono T.Teranishi M.Notani H.Baba S.Nishimura J.Y.Moon M.Nishimura S.Michimasa H.Iwasaki Y.Yanagisawa N.Hokoiwa M.Kibe J.H.Lee S.Kato Y.Gono C.S.Lee 《原子核物理评论》2009,26(Z1)
Proton resonant states in ~(22)Mg have been investigated by the resonant elastic scattering of ~(21)Na+p.The ~(21)Na beam with a mean energy of 4.00 MeV/u was separated by the CNS radioactive ion beam separator(CRIB) and bombarded a thick(CH_2)_n target.The energy spectra of recoiled protons were measured at scattering angles of θ_(cm)~172° and 146°,respectively.A new state at 7.06 MeV has been observed clearly and another new one at 7.28 MeV is tentatively identified due to its low statistics.The proton resonant parameters were deduced from an R-matrix analysis of the differential cross section data.The astrophysical resonant reaction rate for the ~(18)Ne(α,p) ~(21)Na reaction has been estimated,and it is about five times larger than that assumed before. 相似文献
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Bo Mei Dimiter L. Balabanski Wei Hua Yu-Hu Zhang Xiao-Hong Zhou Cen-Xi Yuan Jun Su 《中国物理C(英文版)》2021,45(5):054001-054001-5
Fusion-evaporation cross sections of ~(238)U (~9Be,5n)~(242)Cm are measured over a wide energy range around the Coulomb barrier.These measured cross sections are compared with model calculations using two codes,namely HIVAP2 and KEWPIE2.HIVAP2 calculations overestimate the measured fusion-evaporation cross sections by a factor of approximately 3.In KEWPIE2 calculations,two approaches,namely the Wentzel-Kramers-Brillouin(WKB) approximation and the empirical barrier-distribution (EBD) method,are used for the capture probability;both of them properly describe the measured cross sections.Additionally,fusion cross sections of ~(7,9)Be+~(238)U measured in two experiments are applied to constrain model calculations further through three codes,i.e.,HIVAP2,KEWPIE2,and CCFULL.Parameters in these codes are also examined by comparison with measured fusion cross sections.All the comparisons indicate that the KEWPIE2 calculations using the WKB approximation agree well with the measured cross sections of both fusion reactions ~(7,9)Be+~(238)U and the fusion-evaporation reaction ~(238)U (~9Be,5n)~(242)Cm.Calculations using the fusion code CCFULL are also in good agreement with the measured fusion cross sections of ~(7,9)Be+~(238)U. 相似文献