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Title: Dynamical aspects of isoscaling

Abstract

The origin and dynamical evolution of isoscaling was studied using classical molecular dynamics simulations of {sup 40}Ca+{sup 40}Ca, {sup 48}Ca+{sup 48}Ca, and {sup 52}Ca+{sup 52}Ca at beam energies ranging from 20 to 85 MeV/nucleon. The analysis included a study of the time evolution of this effect. Isoscaling was observed to exist at all energies in these reactions from the early primary isotope distributions (produced by systems not yet in thermal equilibrium) all the way to 5000 fm/c.

Authors:
;  [1]; ;  [2]
  1. Departamento de Fisica, FCEN, Universidad de Buenos Aires, Nunez (Argentina)
  2. Department of Physics, University of Texas at El Paso, El Paso, Texas 79968 (United States)
Publication Date:
OSTI Identifier:
20771455
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 73; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevC.73.044601; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CALCIUM 40; CALCIUM 48; CALCIUM 52; COMPUTERIZED SIMULATION; DISTRIBUTION; HEAVY ION REACTIONS; MEV RANGE; MOLECULAR DYNAMICS METHOD; NUCLEONS; THERMAL EQUILIBRIUM

Citation Formats

Dorso, C.O., Ison, M., Escudero, C.R., and Lopez, J.A.. Dynamical aspects of isoscaling. United States: N. p., 2006. Web. doi:10.1103/PhysRevC.73.044601.
Dorso, C.O., Ison, M., Escudero, C.R., & Lopez, J.A.. Dynamical aspects of isoscaling. United States. doi:10.1103/PhysRevC.73.044601.
Dorso, C.O., Ison, M., Escudero, C.R., and Lopez, J.A.. Sat . "Dynamical aspects of isoscaling". United States. doi:10.1103/PhysRevC.73.044601.
@article{osti_20771455,
title = {Dynamical aspects of isoscaling},
author = {Dorso, C.O. and Ison, M. and Escudero, C.R. and Lopez, J.A.},
abstractNote = {The origin and dynamical evolution of isoscaling was studied using classical molecular dynamics simulations of {sup 40}Ca+{sup 40}Ca, {sup 48}Ca+{sup 48}Ca, and {sup 52}Ca+{sup 52}Ca at beam energies ranging from 20 to 85 MeV/nucleon. The analysis included a study of the time evolution of this effect. Isoscaling was observed to exist at all energies in these reactions from the early primary isotope distributions (produced by systems not yet in thermal equilibrium) all the way to 5000 fm/c.},
doi = {10.1103/PhysRevC.73.044601},
journal = {Physical Review. C, Nuclear Physics},
number = 4,
volume = 73,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • In medium energy heavy ion collisions, fragments are formed in an expanding system. The isospin composition of the produced fragments may reflect the symmetry energy of such low-density nuclear matter. In fact, the simulations by antisymmetrized molecular dynamics (AMD) show that the fragment isospin composition is basically consistent with the statistical expectations even in dynamically evolving system. Isoscaling is satisfied by the AMD results. The width of the fragment isotope distribution can be explained by the ratio of the symmetry energy to the temperature if the symmetry energy at a reduced density is assumed to be relevant. This assumption ismore » justified by studying the dependence on the density-dependent symmetry energy. The symmetry energy extracted from the AMD results is almost independent of the fragment size, which suggests that the fragment isospin composition is governed by the symmetry energy of low-density uniform matter rather than the symmetry energies for isolated nuclei.« less
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  • The symmetry energy and the isoscaling properties of the fragments produced in the multifragmentation of {sup 40}Ar, {sup 40}Ca+{sup 58}Fe, {sup 58}Ni reactions at 25, 33, 45, and 53 MeV/nucleon were investigated within the framework of statistical multifragmentation model. The isoscaling parameters {alpha}, from the primary (hot) and secondary (cold) fragment yield distributions, were studied as a function of excitation energy, isospin (neutron-to-proton asymmetry), and fragment symmetry energy. It is observed that the isoscaling parameter {alpha} decreases with increasing excitation energy and decreasing symmetry energy. The parameter {alpha} is also observed to increase with increasing difference in the isospin ofmore » the fragmenting system. The sequential decay of the primary fragments into secondary fragments, when studied as a function of excitation energy and isospin of the fragmenting system, show very little influence on the isoscaling parameter. The symmetry energy, however, has a strong influence on the isospin properties of the hot fragments. The experimentally observed scaling parameters can be explained by symmetry energy that is significantly lower than that for the ground-state nuclei near saturation density. The results indicate that the properties of hot nuclei at excitation energies, densities, and isospin away from the normal ground-state nuclei could be significantly different.« less