3,260 research outputs found
Halos in medium-heavy and heavy nuclei with covariant density functional theory in continuum
The covariant density functional theory with a few number of parameters has
been widely used to describe the ground-state and excited-state properties for
the nuclei all over the nuclear chart. In order to describe exotic properties
of unstable nuclei, the contribution of the continuum and its coupling with
bound states should be treated properly. In this Topical Review, the
development of the covariant density functional theory in continuum will be
introduced, including the relativistic continuum Hartree-Bogoliubov theory, the
relativistic Hartree-Fock-Bogoliubov theory in continuum, and the deformed
relativistic Hartree-Bogoliubov theory in continuum. Then the descriptions and
predictions of the neutron halo phenomena in both spherical and deformed nuclei
will be reviewed. The diffuseness of the nuclear potentials, nuclear shapes and
density distributions, and the impact of the pairing correlations on nuclear
size will be discussed.Comment: 63 pages; Topical Review, J. Phys. G (in press
Two-Dimensional Steady Supersonic Exothermically Reacting Euler Flow past Lipschitz Bending Walls
We are concerned with the two-dimensional steady supersonic reacting Euler
flow past Lipschitz bending walls that are small perturbations of a convex one,
and establish the existence of global entropy solutions when the total
variation of both the initial data and the slope of the boundary is
sufficiently small. The flow is governed by an ideal polytropic gas and
undergoes a one-step exothermic chemical reaction under the reaction rate
function that is Lipschtiz and has a positive lower bound. The heat released by
the reaction may cause the total variation of the solution to increase along
the flow direction. We employ the modified wave-front tracking scheme to
construct approximate solutions and develop a Glimm-type functional by
incorporating the approximate strong rarefaction waves and Lipschitz bending
walls to obtain the uniform bound on the total variation of the approximate
solutions. Then we employ this bound to prove the convergence of the
approximate solutions to a global entropy solution that contains a strong
rarefaction wave generated by the Lipschitz bending wall. In addition, the
asymptotic behavior of the entropy solution in the flow direction is also
analyzed.Comment: 58 pages, 16 figures; SIAM J. Math. Anal. (accepted on November 1,
2016
Microscopic self-consistent description of induced fission dynamics: finite temperature effects
The dynamics of induced fission of Th is investigated in a
theoretical framework based on the finite-temperature time-dependent generator
coordinate method (TDGCM) in the Gaussian overlap approximation (GOA). The
thermodynamical collective potential and inertia tensor at temperatures in the
interval MeV are calculated using the self-consistent
multidimensionally constrained relativistic mean field (MDC-RMF) model, based
on the energy density functional DD-PC1. Pairing correlations are treated in
the BCS approximation with a separable pairing force of finite range.
Constrained RMF+BCS calculations are carried out in the collective space of
axially symmetric quadrupole and octupole deformations for the asymmetric
fissioning nucleus Th. The collective Hamiltonian is determined by the
temperature-dependent free energy surface and perturbative cranking inertia
tensor, and the TDGCM+GOA is used to propagate the initial collective state in
time. The resulting charge and mass fragment distributions are analyzed as
functions of the internal excitation energy. The model can qualitatively
reproduce the empirical triple-humped structure of the fission charge and mass
distributions already at , but the precise experimental position of the
asymmetric peaks and the symmetric-fission yield can only be accurately
reproduced when the potential and inertia tensor of the collective Hamiltonian
are determined at finite temperature, in this particular case between
MeV and MeV.Comment: 9 pages, 7 figure
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