Seminars & Lectures
|* TITLE||Finite Range Force Models and Nuclear Equation of State|
|* DATE / TIME||2012-08-29, 4pm-5:30pm|
|* PLACE||503 Conference room, APCTP Headquarters, Pohang|
|Nuclear astrophysics is essential to microphysics for the complex
hydrodynamics simulation of numerical supernovae explosions and
neutron star merger calculations. Because many aspects of
equation of state (hereafter, EOS) including symmetry and thermal properties
are uncertain and not well constrained by ex- periments, it is important to
develop EOS with easily adjustable parameters.
First of all, we develop a Finite-Range Thomas Fermi (hereafter, FRTF) model
for supernovae and neutron star matter based on the nuclear model of Seyler
and Blanchard, and Myers and Swiatecki. The nuclear model is extended to finite
temperature and a Wigner-Seitz geometry to model dense matter.
We also extend the model to include additional density dependent
interactions to better fit known nuclear incompressibilities,
pure neutron matter, and the nuclear optical potential.
Using our model, we evaluate nuclear surface properties
using a semi-infinite interface. The coexistence curve of nuclear matter
for two-phase equilibrium is calculated.
Furthermore we calculate energy, radii, and surface thickness of
closed shell nuclei in which the spin-orbit interactions can be neglected.
To get an optimized parameter set for FRTF, we explore the allowed
ranges of symmetry energy and the density derivative of symmetry energy.
We summarize recent experimental results, astrophysical
inference, and theoretical pure neutron matter calculations.
The correlation between symmetry energy and the surface symmetry
energy in liquid droplet model is also obtained. The beta equilibrium matter
is used to model the neutron star crust.
Secondly, we develop a code to compute the nuclear EOS for hot dense matter
that would be distributed to astrophysics community.
With this code, users will be able to generate tables
with adjustable parameters describing the symmetry,
incompressibility, and thermal properties of nuclear matter.
We use the liquid droplet approach to generate thermodynamically
consistent nuclear EOS. table. Compared to previous attempts,
we include neutron skin, Coulumb diffusion, and Coulomb exchange.
In addition, we compute the surface tension as a function of proton
fraction and temperature consistently with the bulk energy.
For comparison, we generate an EOS table using the SLy4 non-relativistic
Skyrme force model. For both FRTF and SLy4, more than 10 % of entries
of EOS tables consists of nuclei, alpha particles, and nucleons.