103 research outputs found
Collective motion in quantum diffusive environment
The general problem of dissipation in macroscopic large-amplitude collective
motion and its relation to energy diffusion of intrinsic degrees of freedom of
a nucleus is studied. By applying the cranking approach to the nuclear
many-body system, a set of coupled dynamical equations for the collective
classical variable and the quantum mechanical occupancies of the intrinsic
nuclear states is derived. Different dynamical regimes of the intrinsic nuclear
motion and its consequences on time properties of collective dissipation are
discussed.Comment: 15 pages, 5 figure
Nucleon distribution in nuclei beyond \beta-stability line
The radii of nucleon distribution, bulk density, and neutron skin in nuclei
beyond the \beta-stability line are studied within the direct variational
method. We evaluate the partial equation of state of finite nuclei and
demonstrate that the bulk density decreases beyond the beta stability line. We
show that the growth of the neutron skin in unstable nuclei does not obey the
saturation condition because of the polarization effect. The value of the
neutron-skin thickness \Delta r_{np}=\sqrt{}-\sqrt{} is caused by
the different radii (skin effect) and only slightly by the different shapes
(halo effect) of neutron and proton distributions. The relative contribution of
both effects depends on the competition between the symmetry energy, and the
spin-orbit and Coulomb interactions. The calculations of the isovector shift of
the nuclear radius \Delta r_{np} show its primarily linear dependence on the
asymmetry parameter X=(N-Z)/A.Comment: 20 pages, 9 figures, published in Phys. Rev. C. arXiv admin note:
text overlap with arXiv:1010.510
Sound modes in hot nuclear matter
The propagation of the isoscalar and isovector sound modes in a hot nuclear
matter is considered. The approach is based on the collisional kinetic theory
and takes into account the temperature and memory effects. It is shown that the
sound velocity and the attenuation coefficient are significantly influenced by
the Fermi surface distortion (FSD). The corresponding influence is much
stronger for the isoscalar mode than for the isovector one. The memory effects
cause a non-monotonous behavior of the attenuation coefficient as a function of
the relaxation time leading to a zero-to-first sound transition with increasing
temperature. The mixing of both the isoscalar and the isovector sound modes in
an asymmetric nuclear matter is evaluated. The condition for the bulk
instability and the instability growth rate in the presence of the memory
effects is studied. It is shown that both the FSD and the relaxation processes
lead to a shift of the maximum of the instability growth rate to the longer
wave length region.Comment: 15 pages, 4 figures, submitted to Phys. Rev.
Giant neutron halo in nuclei beyond beta-stability line
The radii of nucleon distribution and neutron skin in nuclei beyond the
\beta-stability line are studied within the extended Thomas-Fermi
approximation. We show that the growth of neutron skin in unstable nuclei does
not obey the saturation condition because of the neutron coat. The neutron coat
indicates the possibility of giant neutron halo which is growing with moving
away from the beta stability line. We demonstrate the presence of strong shell
oscillations in the charge radius R_C and the relation of R_C to the isospin
shift of neutron-proton chemical potentials \Delta\lambda =\lambda_n-\lambda_p
for nuclei beyond the beta-stability line at fixed value of mass number A.Comment: 10 pages, 6 figures; few sentences and one reference added; published
in Nucl. Phys. At. Energ. V.11, N4, 335 (2010
- …