431 research outputs found
Novel technique to extract experimental symmetry free energy information of nuclear matter
A new method of accessing information on the symmetry free energy from yields
of fragments produced in Fermi-energy heavy-ion collisions is proposed.
Furthermore, by means of quantum fluctuation analysis techniques, correlations
between extracted symmetry free-energy coefficients with temperature and
density were studied. The obtained results are consistent with those of
commonly used isoscaling techniques.Comment: 6 pages, 3 figures Heavy-ion nuclear reactions at Fermi energies,
Nuclear equation of State, Fragmentatio
Experimental determination of the quasi-projectile mass with measured neutrons
The investigation of the isospin dependence of multifragmentation reactions
relies on precise reconstruction of the fragmenting source. The criteria used
to assign free emitted neutrons, detected with the TAMU Neutron Ball, to the
quasi-projectile source are investigated in the framework of two different
simulation codes. Overall and source-specific detection efficiencies for
multifragmentation events are found to be model independent. The equivalence of
the two different methods used to assign experimentally detected charged
particles and neutrons to the emitting source is shown. The method used
experimentally to determine quasi-projectile emitted free neutron multiplicity
is found to be reasonably accurate and sufficiently precise as to allow for the
study of well-defined quasi-projectile sources.Comment: 10 pages, 8 figures. To be submitted to Nucl. Instr. and Meth.
Using Light Charged Particles to Probe the Asymmetry Dependence of the Nuclear Caloric Curve
Recently, we observed a clear dependence of the nuclear caloric curve on
neutron-proton asymmetry through examination of fully
reconstructed equilibrated quasi-projectile sources produced in heavy ion
collisions at E/A = 35 MeV. In the present work, we extend our analysis using
multiple light charged particle probes of the temperature. Temperatures are
extracted with five distinct probes using a kinetic thermometer approach.
Additionally, temperatures are extracted using two probes within a chemical
thermometer approach (Albergo method). All seven measurements show a
significant linear dependence of the source temperature on the source
asymmetry. For the kinetic thermometer, the strength of the asymmetry
dependence varies with the probe particle species in a way which is consistent
with an average emission-time ordering.Comment: 7 pages, 4 figure
Particle-particle correlation functions as an experimental probe of the nuclear asymmetry energy
n/
Mesonic cloud contribution to the nucleon and delta masses
Pion-nucleon elastic scattering in the dominant channel is examined
in the model in which the interaction is of the form . New expressions are found for the elastic pion-nucleon
scattering amplitude which differ from existing formula both in the kinematics
and in the treatment of the renormalization of the nucleon mass and coupling
constant. Fitting the model to the phase shifts in the channel does
not uniquely fix the parameters of the model. The cutoff for the pion-nucleon
form factor is found to lie in the range MeV/c. The masses
of the nucleon and the which would arise if there were no coupling to
mesons are found to be MeV and MeV. The difference in these bare masses, a quantity which would
be accounted for by a residual gluon interaction, is found to be MeV.Comment: 26 pages, 9 figures, significant rewrit
The ASY-EOS experiment at GSI: investigating the symmetry energy at supra-saturation densities
The elliptic-flow ratio of neutrons with respect to protons in reactions of
neutron rich heavy-ions systems at intermediate energies has been proposed as
an observable sensitive to the strength of the symmetry term in the nuclear
Equation Of State (EOS) at supra-saturation densities. The recent results
obtained from the existing FOPI/LAND data for Au+Au collisions
at 400 MeV/nucleon in comparison with the UrQMD model allowed a first estimate
of the symmetry term of the EOS but suffer from a considerable statistical
uncertainty. In order to obtain an improved data set for Au+Au collisions and
to extend the study to other systems, a new experiment was carried out at the
GSI laboratory by the ASY-EOS collaboration in May 2011.Comment: Talk given by P. Russotto at the 11th International Conference on
Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1,
2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference
Series (JPCS
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