共查询到20条相似文献,搜索用时 31 毫秒
1.
Effect of the momentum dependence of nuclear symmetry potential on the transverse and elliptic flows
Lei Zhang Yuan Gao Yun Du Guang-Hua Zuo Gao-Chan Yong 《The European Physical Journal A - Hadrons and Nuclei》2012,48(3):30
In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, the effect of the momentum dependence
of nuclear symmetry potential on nuclear transverse and elliptic flows in the neutron-rich reaction 132Sn+124Sn at a beam energy of 400MeV/nucleon is studied. We find that the momentum dependence of nuclear symmetry potential affects
the rapidity distribution of the free neutron to proton ratio, the neutron and the proton transverse flows as a function of
rapidity. The momentum dependence of nuclear symmetry potential affects the neutron-proton differential transverse flow more
evidently than the difference of neutron and proton transverse flows as well as the difference of proton and neutron elliptic
flows. It is thus better to probe the symmetry energy by using the difference of neutron and proton flows since the momentum
dependence of nuclear symmetry potential is still an open question. And it is better to probe the momentum dependence of nuclear
symmetry potential by using the neutron-proton differential transverse flow the rapidity distribution of the free neutron
to proton ratio. 相似文献
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Some one-neutron halo nuclei can emit a proton in a β decay of the halo neutron. The branching ratio towards this rare decay mode is calculated within a two-body potential model of the initial core + neutron bound state and final core + proton scattering states. The decay probability per second is evaluated for the 11Be, 19C and 31Ne one-neutron halo nuclei. It is very sensitive to the neutron separation energy. 相似文献
4.
在同位旋相关的Brueckner理论框架内, 研究了三体核力重排贡献对同位旋对称势及其动量相关性和密度依赖性的影响,特别是研究了三体核力重排效应对于非对称核物质中质子和中子有效质量同位旋劈裂的影响. 结果表明: 三体核力重排效应对质子和中子单核子势均具有排斥性,而且其贡献随动量和密度增加而迅速增大. 在低密度区域,三体核力重排贡献对同位旋对称势的影响相当小,然而随着密度的升高,三体核力重排效应的贡献显著增强. 在高密度区域,三体核力重排效应使得同位旋对称势明显增大,而且当密度足够高时,三体核力重排贡献甚至导致对称势的动量相关性质发生改变. 三体核力的重排效应对核子有效质量同位旋依赖性的影响是使高密度丰中子核物质中质子-中子有效质量同位旋劈裂的幅度显著减小. 相似文献
5.
We investigate nucleon mass splitting at finite isospin chemical potential in the frame of the two-flavour Nambu-Jona-Lasinio model. It is analytically proven that in the phase with explicit isospin symmetry breaking, the proton mass decreases and the neutron mass increases linearly in the isospin chemical potential. 相似文献
6.
《Nuclear Physics A》1999,652(3):250-270
We investigate the ground state properties of proton-rich nuclei in the framework of the relativistic mean-field model. Calculations show that the experimental proton halo in the nuclei 26,27,28P can be reproduced by the model. The proton halos can appear in proton-rich nuclei because the total nuclear potential is attractive up to the radial distance r ≈ 5.5 fm. But the size of proton halos is finite due to the limitation of the Coulomb potential barrier. The mean-square radius of a halo proton is not very sensitive to the separation energy of the last proton in some very proton-rich nuclei due to the effect of the Coulomb barrier. This behavior is different from the case of a neutron halo where the mean-square radius of a halo neutron is inversely proportional to the separation energy of the last halo neutron. We have also analysed the differences of the relativistic mean-field potentials of 25Al and 26P and found that the isovector potential from the p meson has an important effect on the differences. 相似文献
7.
在Walecka模型的平均场近似下,研究了由质子、中子和电子组成的中子星物质在均匀强磁场中的性质,发现磁场增强,物态方程会在一定程度上变硬,中子所占比例显著增加,质子和电子所占比例会显著减少,磁场对物态方程的影响比它对粒子组分的影响小.本文还分别利用流体力学公式和热力学公式分别计算了中子星物质的压强,发现磁场越强,用这两种方式计算的压强越接近,当磁场为1014T时,它们完全重合. 相似文献
8.
Guan-Ying Wang Ran Han Xiao-Ping Ouyang Jin-Cheng He Jun-Yao Yan 《中国物理C(英文版)》2017,41(5):056201-056201
A reconstruction algorithm for unfolding neutron energy spectra has been developed, based for the first time on the potential reduction interior point algorithm. This algorithm can be easily applied to neutron energy spectrum reconstruction in the recoil proton method. We transform the neutron energy spectrum unfolding problem into a typical nonnegative linear complementarity problem. The recoil proton energy spectrum and response matrix at angles of 0^o and 30^o are generated by the Geant4 simulation toolkit. Several different neutron energy test spectra are also employed. It is found that this unfolding algorithm is stable and provides efficient, accurate results. 相似文献
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《Nuclear Physics A》1987,462(3):413-444
Differential cross sections for the elastic scattering of neutrons from 40Ca have been measured in the 19–26 MeV region. The neutron elastic scattering data, previous neutron measurements and additional proton elastic scattering data are analyzed using three different approaches to the optical model potential: Woods-Saxon parameterization, model independent analysis and microscopic calculations. The difference between the phenomenological neutron and proton real potentials is studied in terms of Coulomb effects, nuclear polarization and charge symmetry breaking in the nuclear mean field. 相似文献
11.
在光学势中引入色散关系, 相比于通常的耦合道光学模型, 极大地减少了光学势
参数的个数. 采用基于软旋转子模型的耦合道方法对较轻形变核28Si核的中子和质子散射实验数据进行了计算分析, 拟合得到一组色散光学势参数. 计算的中子总截面、以及中子、质子的弹性与非弹性散射微分截面与实验数据有较好的符合. 相似文献
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O. V. Bespalova A. A. Klimochkina A. V. Korotkov T. I. Spasskaya 《Moscow University Physics Bulletin》2017,72(1):51-60
The neutron and proton dispersive optical potential for the 208Pb nucleus has been determined for the energy region from–70 to +60 MeV and used to calculate the differential elastic scattering, the total interaction and reaction cross sections, as well as the single-particle characteristics, the neutron and charge densities, rms radii, and the thickness of the nucleus skin. The calculated results are in good agreement with the experimental data. The proton dispersive optical model potential for the spherical and close to spherical Pb isotopes within the neutron and proton drip lines has been obtained by a similar method. The calculation predicts a trend towards the growth of the proton particle-hole gap, which corresponds to Z = 82 shell closure as Z approaches the proton drip line. 相似文献
15.
A. Schett A. St. Schirmaier J. W. Weil 《Zeitschrift für Physik A Hadrons and Nuclei》1967,206(1):18-28
The relation between the parameters of the optical potential of the deuteron and those of its constituent nucleons is investigated. An analytical expression for the real depth of the deuteron potential is derived, where it is represented as the sum of the proton and neutron real potentials minus a correction factor. Optical model analysis is carried out for deuteron and proton elastic scatterings in order to test the derived relation. 相似文献
16.
在Brueckner-Hartree-Fock理论框架内, 研究了同位旋非对称核物质中质子和中子单粒子势的动量相关性及其随同位旋非对称度的变化, 在此基础上计算了同位旋对称势, 并讨论了三体核力的影响. 结果表明同位旋对称势对于同位旋非对称度的依赖性很弱, 但对于动量和密度均有较强的依赖性. 当密度固定时, 同位旋对称势随动量增加而减小. 尽管三体核力对于质子和中子单粒子势的动量相关性有较大影响, 但对同位旋对称势的影响很小. 还与目前重离子碰撞输运理论模型中所使用的各种参数化的唯象对称势进行了比较. 相似文献
17.
中能重离子碰撞中的中子(质子)发射的同位旋效应 总被引:1,自引:0,他引:1
利用同位旋相关的量子分子动力学,对中能重离子碰撞过程中的中子和质子发射的同位旋效应进行了分析.计算结果表明在有动量相关作用条件下,在很宽的能量和碰撞参数范围内,缺中子碰撞系统的中子(质子)发射数强烈地依赖于同位旋相关的核子–核子碰撞截面,而较弱地依赖于对称势.在对丰中子碰撞系统的研究中,上述规律减弱.这样就可以通过实验上对缺中子碰撞系统的中子(质子)发射数的探测,来提取介质中同位旋相关核子–核子碰撞截面的知识. 相似文献
18.
Impact Parameter Dependence of the Double Neutron/Proton Ratio of Nucleon Emissions in Isotopic Reaction Systems
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Within the transport model IBUU04, we investigate the double neutron/proton ratio of free nucleons taken from two reaction systems using two Sn isotopes at a beam energy of 50 MeV/nucleon and with impact parameters 2fm, 4fm and 8fm, respectively. It is found that the double neutron/proton ratio from peripheral collisions is more sensitive to the density dependence of the symmetry energy than those from mid-central and central collisions. 相似文献
19.
M. Tohyama 《Nuclear Physics A》1983,401(2):211-236
The isotope dependence of the widths of the hole analog states is studied for the Zr, Mo and Sn isotopes. In order to calculate the proton escape widths, we propose a microscopic model, in which the coupling of a neutron hole state to the isobaric analog state of the core is considered. It is found that the proton escape widths carry the observed isotope dependence of the widths of the hole analog states and that the isotope dependence of the proton escape widths is caused by two effects: the isotope dependence of the maximum available energy for a decaying proton, and that of the occupation probabilities of the excess neutron orbits in the parent state. 相似文献
20.
Nuclear shell model calculations based on a modified harmonic-oscillator potential result in amazingly stable triaxial nuclear shapes. Major gaps in the single-particle energy spectra at proton number 71 and neutron number 94 combine constructively at low and intermediate rotational frequencies. At high frequencies, gaps at proton number 72 and neutron number 97 combine in an equally favourable way. The sizes of the gaps may be as large as 35% of the values for the gaps at the classical magic numbers 50 and 82 at spherical shape. The dependence on the positions of the intruder levels in forming the gaps is discussed. Experimentally observed rotational bands in lutetium (Z = 71) and hafnium (Z = 72) appear in isotopes and frequency ranges, which are consistent with the gaps in the theoretical single-particle energy spectra. 相似文献