521 research outputs found
Dynamics of Multifragmentation in Heavy Ion Collisions
We review multifragmentation data obtained at the SIS/GSI accelerator using
heavy ion beams with (0.1-1)A GeV together with the ALADIN and FOPI
experimental setups.Comment: 25 pages, with 38 included figures; invited talk at the
Nishinomiya-Yukawa Symposium on Frontiers of Nuclear Collision Dynamics,
Japan (nov.18-19); to be published in Progress of Theoretical Physic
Medium mass fragments production due to momentum dependent interactions
The role of system size and momentum dependent effects are analyzed in
multifragmenation by simulating symmetric reactions of Ca+Ca, Ni+Ni, Nb+Nb,
Xe+Xe, Er+Er, Au+Au, and U+U at incident energies between 50 MeV/nucleon and
1000 MeV/nucleon and over full impact parameter zones. Our detailed study
reveals that there exist a system size dependence when reaction is simulated
with momentum dependent interactions. This dependence exhibits a mass power law
behavior.Comment: 5 figure
Modelling incomplete fusion dynamics of weakly-bound nuclei at near-barrier energies
The classical dynamical model for reactions induced by weakly-bound nuclei at
near-barrier energies is developed further. It allows a quantitative study of
the role and importance of incomplete fusion dynamics in asymptotic
observables, such as the population of high-spin states in reaction products as
well as the angular distribution of direct alpha-production. Model calculations
indicate that incomplete fusion is an effective mechanism for populating
high-spin states, and its contribution to the direct alpha production yield
diminishes with decreasing energy towards the Coulomb barrier. It also becomes
notably separated in angles from the contribution of no-capture breakup events.
This should facilitate the experimental disentanglement of these competing
reaction processes.Comment: 12 pages, 7 figures (for better resolution figures please contact the
author), Accepted in Journal of Physics
A modified proximity approach in the fusion of heavy-ions
By using a suitable set of the surface energy coefficient, nuclear radius,
and universal function, the original proximity potential 1977 is modified. The
overestimate of the data by 4 % reported in the literature is significantly
reduced. Our modified proximity potential reproduces the experimental data
nicely compared to its older versions.Comment: 9 pages, 5 figures, Chin. Phys. lett.(2010) in pres
Competition of fusion and quasi-fission in the reactions leading to production of the superheavy elements
The mechanism of fusion hindrance, an effect observed in the reactions of
cold, warm and hot fusion leading to production of the superheavy elements, is
investigated. A systematics of transfermium production cross sections is used
to determine fusion probabilities. Mechanism of fusion hindrance is described
as a competition of fusion and quasi-fission. Available evaporation residue
cross sections in the superheavy region are reproduced satisfactorily. Analysis
of the measured capture cross sections is performed and a sudden disappearance
of the capture cross sections is observed at low fusion probabilities. A
dependence of the fusion hindrance on the asymmetry of the projectile-target
system is investigated using the available data. The most promising pathways
for further experiments are suggested.Comment: 8 pages, 7 figures, talk presented at 7th International
School-Seminar on Heavy-Ion Physics, May 27 - June 1, 2002, Dubna, Russi
Modelling of compound nucleus formation in fusion of heavy nuclei
A new model that includes the time-dependent dynamics of the single-particle
(s.p.) motion in conjunction with the macroscopic evolution of the system is
proposed for describing the compound nucleus (CN) formation in fusion of heavy
nuclei. The diabaticity initially keeps the entrance system around its contact
configuration, but the gradual transition from the diabatic to the adiabatic
potential energy surface (PES) leads to fusion or quasifission. Direct
measurements of the probability for CN formation are crucial to discriminate
between the current models.Comment: 4 pages,2 figures,1 table, Submitted to PR
Collective flow in central Au-Au collisions at 150, 250 and 400 A MeV
Radial collective flow and thermalization are studied in gold on gold
collisions at 150, 250 and 400 A MeV bombarding energies with a
relativistically covariant formulation of a QMD code. We find that radial flow
and "thermal" energies calculated for all the charged fragments agree
reasonably with the experimental values. The experimental hardware filter at
small angles used in the FOPI experiments at higher energies selects mainly the
thermalized particles.Comment: 4 pages with 4 EPS figures included. Version accepted for publication
in Phys. Rev.
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