K.C. Chung

Isospin Dependence in Nuclear Multifragmentation Within Site Percolation and Nucleation Pictures

The isospin dependence, recently observed in reactions at , is discussed within the framework of two simple nuclear multifragmentation models, namely the site percolation and the nucleation-evaporation models. It is shown that both the models are able to discriminate between and reactions. The nucleation-evaporation model succeeds to reproduce nicely the experimental data, but the site percolation model fails in doing that, even if the cluster noncompactive effect is taken into account. The calculations indicate that the data are originated mainly from a single source.

Effective nucleon-nucleon interactions and nuclear matter equation of state

Abstract:Nuclear matter equations of state based on Skyrme, Myers-Swiatecki and Tondeur interactions are written as polynomials of the cubic root of density, with coefficients that are functions of the relative neutron excess δ. In the extrapolation toward states far away from the standard one, it is shown that the asymmetry dependence of the critical point ( ,) depends on the model used. However, when the equations of state are fitted to the same standard state, the value of is almost the same in Skyrme and in Myers-Swiatecki interactions, while is much lower in Tondeur interaction. Furthermore, does not depend sensitively on the choice of the parameter γ in Skyrme interaction.

Extraction of Nuclear Matter Properties from Nuclear Masses by a Model of Equation of State

The extraction of nuclear matter properties from measured nuclear masses is investigated in the energy density functional formalism of nuclei.It is shown that the volume energy and the nuclear incompressibility depend essentially on ,whereas the symmetry energy and the density symmetry coefficient as well as symmetry incompressibility depend essentially on ,where , and are the neutron and proton chemical potentials respectively, the nuclear energy,and the Coulomb energy.The obtained symmetry energy is , while other coefficients are uncertain within ranges depending on the model of nuclear equation of state.

Nuclear matter properties and relativistic mean-field theory

Abstract:Nuclear matter properties are calculated in the relativistic mean-field theory by using a number of different parameter sets. The result shows that the volume energy a1 and the symmetry energy J are around the acceptable values 16MeV and 30MeV, respectively; the incompressibility K0 is unacceptably high in the linear model, but assumes reasonable value if nonlinear terms are included; the density symmetry L is around 100MeV for most parameter sets, and the symmetry incompressibility Ks has positive sign which is opposite to expectations based on the nonrelativistic model. In almost all parameter sets there exists a critical point (,), where the minimum and the maximum of the equation of state are coincident and the incompressibility equals zero, falling into ranges 0.014fm^-3 < < 0.039fm^-3 and 0.74 < ≤0.95; for a few parameter sets there is no critical point and the pure neutron matter is predicted to be bound. The maximum mass MNS of neutron stars is predicted in the range 2.45M?MNS? 3.26M, the corresponding neutron star radius RNS is in the range 12.2km ?RNS? 15.1km.

Nuclear matter properties in relativistic mean-field model with σ- ω coupling

Abstract:The σ-ω coupling is introduced phenomenologically in the linear σ-ω model to study the nuclear matter properties. It is shown that not only the effective nucleon mass M* but also the effective σ meson mass mσ* and the effective ω meson mass mω* are nucleon-density-dependent. When the model parameters are fitted to the nuclear saturation point, with the nuclear radius constant r0 = 1.14 fm and volume energy a1 = 16.0 MeV, as well as to the effective nucleon mass M* = 0.85M, the model yields mσ* = 1.09mσ and mω* = 0.90mω at the saturation point, and the nuclear incompressibility K0 = 501 MeV. The lowest value of K0 given by this model by adjusting the model parameters is around 227 MeV.

Nuclear fragmentation in nucleus–nucleus reaction within a two-lattices percolation picture

It is shown that elemental multiplicity distributions, relative abundances of intermediate mass fragments as well as fragment kinetic energy spectra and charged-particle correlations in nucleus-nucleus induced multi-fragmentation reactions can be satisfactorily reproduced by site percolation procedure in the case that the occupation probability is taken explicitly as a function of the geometry of the collision.