4 research outputs found
Constraining nucleon effective masses with flow and stopping observables from the SRIT experiment
Properties of the nuclear equation of state (EoS) can be probed by measuring
the dynamical properties of nucleus-nucleus collisions. In this study, we
present the directed flow (), elliptic flow () and stopping (VarXZ)
measured in fixed target Sn + Sn collisions at 270 AMeV with the SRIT Time
Projection Chamber. We perform Bayesian analyses in which EoS parameters are
varied simultaneously within the Improved Quantum Molecular Dynamics-Skyrme
(ImQMD-Sky) transport code to obtain a multivariate correlated constraint. The
varied parameters include symmetry energy, , and slope of the symmetry
energy, , at saturation density, isoscalar effective mass, ,
isovector effective mass, and the in-medium cross-section
enhancement factor . We find that the flow and VarXZ observables are
sensitive to the splitting of proton and neutron effective masses and the
in-medium cross-section. Comparisons of ImQMD-Sky predictions to the SRIT
data suggest a narrow range of preferred values for ,
and
Isoscaling in central Sn+Sn collisions at 270 MeV/u
Experimental information on fragment emissions is important in understanding
the dynamics of nuclear collisions and in the development of transport model
simulating heavy-ion collisions. The composition of complex fragments emitted
in the heavy-ion collisions can be explained by statistical models, which
assume that thermal equilibrium is achieved at collision energies below 100
MeV/u. Our new experimental data together with theoretical analyses for light
particles from Sn+Sn collisions at 270 MeV/u, suggest that the hypothesis of
thermal equilibrium breaks down for particles emitted with high transfer
momentum. To inspect the system's properties in such limit, the scaling
features of the yield ratios of particles from two systems, a neutron-rich
system of and a nearly symmetric
system of , are examined in the
framework of the statistical multifragmentation model and the antisymmetrized
molecular dynamics model. The isoscaling from low energy particles agree with
both models. However the observed breakdown of isoscaling for particles with
high transverse momentum cannot be explained by the antisymmetrized molecular
dynamics model