79 research outputs found
Pre-scission neutron multiplicity associated with the dynamical process in superheavy mass region
The fusion-fission process accompanied by neutron emission is studied in the
superheavy-mass region on the basis of the fluctuation-dissipation model
combined with a statistical model. The calculation of the trajectory or the
shape evolution in the deformation space of the nucleus with neutron emission
is performed. Each process (quasi-fission, fusion-fission, and deep
quasi-fission processes) has a characteristic travelling time from the point of
contact of colliding nuclei to the scission point. These dynamical aspects of
the whole process are discussed in terms of the pre-scission neutron
multiplicity, which depends on the time spent on each process. We have
presented the details of the characteristics of our model calculation in the
reactions Ca+Pb and Ca+Pu, and shown how the
structure of the distribution of pre-scission neutron multiplicity depends on
the incident energy.Comment: 19 pages, 12 figures, Accepted for publication in J. Phys.
Fusion hindrance and roles of shell effects in superheavy mass region
We present the first attempt of systematically investigating the effects of
shell correction energy for a dynamical process, which includes fusion,
fusion-fission and quasi-fission processes. In the superheavy mass region, for
the fusion process, shell correction energy plays a very important role and
enhances the fusion probability when the colliding partner has a strong shell
structure. By analyzing the trajectory in three-dimensional coordinate space
with the Langevin equation, we reveal the mechanism of the enhancement of the
fusion probability caused by `cold fusion valleys'. The temperature dependence
of shell correction energy is considered.Comment: 31 pages, 23 figures, Accepted for publication in Nuclear Physics
Analysis of fusion-fission dynamics by pre-scission neutron emission in Ni+Pb
We analyzed the experimental data of the pre-scission neutron multiplicity in
connection with fission fragments in the reaction Ni+Pb at the
incident energy corresponding to the excitation energy of compound nucleus
=185.9 MeV, which was performed by D\'{e}MoN group. The relation between
the pre-scission neutron multiplicity and each reaction process having
different reaction time is investigated. In order to study the fusion-fission
process accompanied by neutron emission, the fluctuation-dissipation model
combined with a statistical model is employed. It is found that the
fusion-fission process and the quasi-fission process are clearly distinguished
in correlation with the pre-scission neutron multiplicity.Comment: 11 figure
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