Article

# Study of Isoscaling with Statistical Multifragmentation Models

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06/2001;
Source: arXiv

ABSTRACT

Different statistical multifragmentation models have been used to study isoscaling, i.e. the factorization of the isotope ratios from two reactions, into fugacity terms of proton and neutron number, R21(N,Z)=Y2(N,Z)/Y1(N,Z)=C*exp(a*N+b*Z). Even though the primary isotope distributions are quite different from the final distributions due to evaporation from the excited fragments, the values of a and b are not much affected by sequential decays. a is shown to be mainly sensitive to the proton and neutron composition of the emitting source and may be used to study isospin-dependent properties in nuclear collisions such as the symmetry energy in the equation of state of asymmetric nuclear matter.

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• "where α and β are fitting parameters. Equations of the form of (1) can be linked, under some approximations, to primary isotope yields produced by disassembling infinite equilibrated systems in microcanonical and grand canonical ensembles [4], as well as to breakups in canonical [6] ensembles. Little reflection is needed to understand that R 21 could be affected by many reaction variables. "
##### Article: Dynamical aspects of isoscaling
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ABSTRACT: The origin and dynamical evolution of isoscaling was studied using classical molecular dynamics simulations of ${}^{40}$Ca + ${}^{40}$Ca, ${}^{48}$Ca + ${}^{48}$Ca, and ${}^{52}$Ca + ${}^{52}$Ca, at beam energies ranging from $20 \ MeV/A$ to $85 MeV/A$. The analysis included a study of the time evolution of this effect. Isoscaling was observed to exist in these reactions from the very early primary isotope distributions (produced by highly {\it non-equilibrated} systems) all the way to asymptotic times. This indicates that isoscaling is independent of quantum effects and thermodynamical equilibrium. In summary, collision-produced isoscaling appears to be due more to the mere partitioning of the proton-neutron content of the participant nuclei, than to specific details of the reaction dynamics.
Physical Review C 04/2005; 73(4). DOI:10.1103/PhysRevC.73.044601 · 3.73 Impact Factor
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##### Article: Comparison of Canonical and Grand Canonical Models for selected multifragmentation data
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ABSTRACT: Calculations for a set of nuclear multifragmentation data are made using a Canonical and a Grand Canonical Model. The physics assumptions are identical but the Canonical Model has an exact number of particles, whereas, the Grand Canonical Model has a varying number of particles, hence, is less exact. Interesting differences are found. Comment: 12 pages, Revtex, and 3 postscript figures
Physical Review C 06/2001; 64(4). DOI:10.1103/PhysRevC.64.044608 · 3.73 Impact Factor
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##### Article: Fragile Signs of Criticality in the Nuclear Multifragmentation
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ABSTRACT: Deviations from an idealized equilibrium phase transition picture in nuclear multifragmentation is studied in terms of the entropic index. We investigate different heat-capacity features in the canonical quantum statistical model of nuclear multifragmentation generalized in the framework of Tsallis nonextensive thermostatistics. We find that the negative branch of heat capacity observed in quasi-peripheral Au+Au collisions is caused primarily by the non-generic nonextensivity effects.
Acta Physica Polonica Series B 07/2001; 33(7). · 0.85 Impact Factor