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Mass and charge distributions for the reaction {sup 40}Ca + {sup 209}Bi at 600 MeV

Journal Article · · Physical Review, C
; ; ; ;  [1];  [2]
  1. Chemistry Department, University of Maryland, College Park, Maryland 20742 (United States)
  2. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
The charge and mass of the projectile-like fragments produced in the 15-MeV per nucleon {sup 40}Ca+{sup 209}Bi reaction were determined for products detected near the grazing angle. Neutron number-charge ({ital N}{minus}{ital Z}) distributions were generated as a function of the total kinetic energy loss and parametrized by their centroids, variances, and correlation coefficients. Although the initial system is very asymmetric, after the interaction, a drift of the charge and mass centroids toward further asymmetry is observed. The production of projectile-like fragments is consistent with a tendency of the projectile-like fragments to retain the projectile neutron-to-proton ratio {l_angle}{ital N}{r_angle}/{l_angle}{ital Z}{r_angle}{congruent}1. The correlation coefficient remains well below 1.0 for the entire range of total kinetic energy lost. Predictions of two nucleon exchange models, Randrup`s and Tassan-Got`s, are compared to the experimental results. The models are not able to reproduce the evolution of the experimental distributions, especially the fact that the variances reach a maximum and then decrease as function of the energy loss. This behavior supports the hypothesis that some form of projectile-like fragmentation or cluster emission is perturbing the product distribution from that expected from a damped mechanism.
DOE Contract Number:
FG02-93ER40802; FG05-87ER40321
OSTI ID:
132942
Journal Information:
Physical Review, C, Journal Name: Physical Review, C Journal Issue: 6 Vol. 52; ISSN PRVCAN; ISSN 0556-2813
Country of Publication:
United States
Language:
English