155 research outputs found
Heavy-ion Collisions: Direct and indirect probes of the density and temperature dependence of Esym
Heavy-ion collisions provide a versatile terrestrial probe of the nuclear
equation of state through the formation of nuclear matter at a wide variety of
temperatures, densities, and pressures. Direct and indirect approaches for
constraining the density dependence of the symmetry energy using heavy-ion
collisions have been developed. The direct approach relies on scaling methods
which attempt to connect isotopic fragment distributions to the symmetry
energy. Using the indirect approach constraints on the equation of state are
extracted from comparison of experimental results and theoretical transport
calculations which utilize effective nucleon-nucleon interactions. Besides
exploring the density dependence of the equation of state, heavy-ion collisions
are simultaneously probing different temperature gradients of nuclear matter
allowing for the temperature dependence of the symmetry energy to be examined.
The current progress and open questions related to constraining the density and
temperature dependence of the symmetry energy with heavy-ion collisions are
discussed in the review.Comment: Review to appear in the upcoming EPJA special volume on nuclear
symmetry energ
Exploiting neutron-rich radioactive ion beams to constrain the symmetry energy
The Modular Neutron Array (MoNA) and 4 Tm Sweeper magnet were used to measure
the free neutrons and heavy charged particles from the radioactive ion beam
induced 32Mg + 9Be reaction. The fragmentation reaction was simulated with the
Constrained Molecular Dynamics model(CoMD), which demonstrated that the
of the heavy fragments and free neutron multiplicities were observables
sensitive to the density dependence of the symmetry energy at sub-saturation
densities. Through comparison of these simulations with the experimental data
constraints on the density dependence of the symmetry energy were extracted.
The advantage of radioactive ion beams as a probe of the symmetry energy is
demonstrated through examination of CoMD calculations for stable and
radioactive beam induced reactions
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.
Three-body correlations in the ground-state decay of 26O
Background: Theoretical calculations have shown that the energy and angular
correlations in the three-body decay of the two-neutron unbound O26 can provide
information on the ground-state wave function, which has been predicted to have
a dineutron configuration and 2n halo structure.
Purpose: To use the experimentally measured three-body correlations to gain
insight into the properties of O26, including the decay mechanism and
ground-state resonance energy.
Method: O26 was produced in a one-proton knockout reaction from F27 and the
O24+n+n decay products were measured using the MoNA-Sweeper setup. The
three-body correlations from the O26 ground-state resonance decay were
extracted. The experimental results were compared to Monte Carlo simulations in
which the resonance energy and decay mechanism were varied.
Results: The measured three-body correlations were well reproduced by the
Monte Carlo simulations but were not sensitive to the decay mechanism due to
the experimental resolutions. However, the three-body correlations were found
to be sensitive to the resonance energy of O26. A 1{\sigma} upper limit of 53
keV was extracted for the ground-state resonance energy of O26.
Conclusions: Future attempts to measure the three-body correlations from the
ground-state decay of O26 will be very challenging due to the need for a
precise measurement of the O24 momentum at the reaction point in the target
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