61 research outputs found
Fusion Hindrance in the Heavy Ion Reactions -- Border Between the Normal and Hindered Fusions
The fusion hindrance in heavy ion collisions is studied in the framework of
the two-center liquid drop model. It appears that the neck and the radial
degrees of freedom might both be hampered by an inner potential barrier on
their path between the contact configuration to the compound nucleus. Heavy ion
reactions with and without the two kinds of fusion hindrance are classified
through systematic calculations. It is found that the number of reactions
without radial fusion hindrance is much smaller than that without neck fusion
hindrance, and for both kinds of fusion hindrance the number of reactions
without fusion hindrance at small mass-asymmetry parameter is smaller
than that at large . In the formation of a given compound nucleus, if a
reaction with is not hindered, then other reactions with are also not hindered as it is well known experimentally.Comment: 14 pages, 7 figure
Probing the momentum dependence of medium modifications of the nucleon-nucleon elastic cross sections
The momentum dependence of the medium modifications on nucleon-nucleon
elastic cross sections is discussed with microscopic transport theories and
numerically investigated with an updated UrQMD microscopic transport model. The
semi-peripheral Au+Au reaction at beam energy MeV is adopted as an
example. It is found that the uncertainties of the momentum dependence on
medium modifications of cross sections influence the yields of free nucleons
and their collective flows as functions of their transverse momentum and
rapidity. Among these observables, the elliptic flow is sensitively dependent
on detailed forms of the momentum dependence and more attention should be paid.
The elliptic flow is hardly influenced by the probable splitting effect of the
neutron-neutron and proton-proton cross sections so that one might pin down the
mass splitting effect of the mean-field level at high beam energies and high
nuclear densities by exploring the elliptic flow of nucleons or light clusters.Comment: 13 pages, 6 figures, 1 tabl
Residue cross sections of Ti-induced fusion reactions based on the two-step model
Ti-induced fusion reactions to synthesize superheavy elements are
studied systematically with the two-step model developed recently, where fusion
process is divided into approaching phase and formation phase. Furthermore, the
residue cross sections for different neutron evaporation channels are evaluated
with the statistical evaporation model. In general, the calculated cross
sections are much smaller than that of Ca-induced fusion reactions, but
the results are within the detection capability of experimental facilities
nowadays. The maximum calculated residue cross section for producing superheavy
element is in the reaction Ti+Bk in channels with
pb at = 37.0 MeV.Comment: 6 pages, 7 figure
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