93,393 research outputs found
Can the nuclear symmetry potential at supra-saturation densities be negative?
In the framework of an Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU)
transport model, for the central Au+Au reaction at an incident
beam energy of 400 MeV/nucleon, effect of nuclear symmetry potential at
supra-saturation densities on the pre-equilibrium clusters emission is studied.
It is found that for the positive symmetry potential at supra-saturation
densities the neutron to proton ratio of lighter clusters with mass number
() is larger than that of the weighter clusters with
mass number (), whereas for the negative symmetry potential
at supra-saturation densities the is \emph{smaller} than that
of the . This may be considered as a probe of the negative
symmetry potential at supra-saturation densities.Comment: 5 pages, 3 figures, 1 table, to be publishe
Quantum Langevin model for exoergic ion-molecule reactions and inelastic processes
We presents a fully quantal version of the Langevin model for the total rate
of exoergic ion-molecule reactions or inelastic processes. The model, which is
derived from a rigorous multichannel quantum-defect formulation of bimolecular
processes, agrees with the classical Langevin model at sufficiently high
temperatures. It also gives the first analytic description of ion-molecule
reactions and inelastic processes in the ultracold regime where the quantum
nature of the relative motion between the reactants becomes important.Comment: 5 pages, 3 figure
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