688 research outputs found
Hydrodynamics of a quark droplet II: Implications of a non-zero baryon chemical potential
We present an extended version of the dynamical model for a multi-quark
droplet evolution described in our proceeding paper. The model includes
collective expansion of the droplet, effects of the vacuum pressure and surface
tension, and now a non-zero baryon number. The hadron emission from the droplet
is described following Weisskopf's statistical model. We consider evolutions of
droplets with different initial temperatures and net baryon number. It is found
that the introduction of a non-zero net baryon number does not change the
lifetime of the droplets significantly. Only when we consider an initially very
baryon-rich, low-temperature droplets is the lifetime is decreased
significantly. We have, furthermore, found a convergence of both baryon
chemical potential and temperature toward the values 450
MeV and MeV. This convergence is linked to the competing
emission of baryons versus mesons.Comment: 15 pages, 5 figure
Correlation studies of fission fragment neutron multiplicities
We calculate neutron multiplicities from fission fragments with specified
mass numbers for events having a specified total fragment kinetic energy. The
shape evolution from the initial compound nucleus to the scission
configurations is obtained with the Metropolis walk method on the
five-dimensional potential-energy landscape, calculated with the
macroscopic-microscopic method for the three-quadratic-surface shape family.
Shape-dependent microscopic level densities are used to guide the random walk,
to partition the intrinsic excitation energy between the two proto-fragments at
scission, and to determine the spectrum of the neutrons evaporated from the
fragments. The contributions to the total excitation energy of the resulting
fragments from statistical excitation and shape distortion at scission is
studied. Good agreement is obtained with available experimental data on neutron
multiplicities in correlation with fission fragments from U(n,f). At higher neutron energies a superlong fission mode appears which
affects the dependence of the observables on the total fragment kinetic energy.Comment: 12 pages, 10 figure
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