9,595 research outputs found
Investigation of the quasifission process by theoretical analysis of experimental data of fissionlike reaction products
The fusion excitation function is the important quantity in planning
experiments for the synthesis of superheavy elements. Its values seem to be
determined by the experimental study of the hindrance to complete fusion by the
observation of mass, angular and energy distributions of the fissionlike
fragments. There is ambiguity in establishment of the reaction mechanism
leading to the observed binary fissionlike fragments. The fissionlike fragments
can be produced in the quasifission, fast fission, and fusion-fission processes
which have overlapping in the mass (angular, kinetic energy) distributions of
fragments. The branching ratio between quasifission and complete fusion
strongly depends on the characteristics of the entrance channel. In this paper
we consider a wide set of reactions (with different mass asymmetry and mass
symmetry parameters) with the aim to explain the role played by many quantities
on the reaction mechanisms. We also present the results of study of the
Ca+Bk reaction used to synthesize superheavy nuclei with Z = 117
by the determination of the evaporation residue cross sections and the
effective fission barriers of excited nuclei formed along the
de-excitation cascade of the compound nucleus.Comment: 21 pages, 15 figures, 2 table
Pion Polarizability in the NJL model and Possibilities of its Experimental Studies in Coulomb Nuclear Scattering
The charge pion polarizability is calculated in the Nambu-Jona-Lasinio model,
where the quark loops (in the mean field approximation) and the meson loops (in
the approximation) are taken into account. We show that quark loop
contribution dominates, because the meson loops strongly conceal each other.
The sigma-pole contribution plays the main role and
contains strong t-dependence of the effective pion polarizability at the region
. Possibilities of experimental test of this sigma-pole
effect in the reaction of Coulomb Nuclear Scattering are estimated for the
COMPASS experiment.Comment: 11 pages, 8 figure
- …