engleski

Comprehensive analysis of fusion data well above the barrier

We report on the comprehensive systematics of nearly 400 fusion-evaporation and/or fusion- fission cross section data for a very large variety of systems over an energy range similar to 3A to 155A MeV. Scaled by the reaction cross section and expressed as a function of the center- of-mass energy per nucleon, the fusion cross section displays a universal behavior. Within experimental errors, this behavior does not depend on system mass, mass asymmetry, or system isospin. The deduced homographic functional dependence for complete and summed complete and incomplete fusion excitation functions is derived from basic strong absorption model formulas for reaction cross sections and allows us to draw the main properties of these functions. The limiting energy for the complete fusion and the main characteristics (onset, maximum, and extinction) of the incomplete fusion excitation functions are determined. The complete fusion reaction process disappears around 6.5 MeV/nucleon and the incomplete one disappears at about 13 MeV/nucleon in the center-of-mass frame. The regularity in fusion data is particularly obvious for the evaporation-residue subset of the data ensemble. Adding the fusion- fission data component does not alter the general data trend but somewhat obscures it owing to the larger uncertainty and/or possible normalization problems.

Heavy-ion reactions; Intermediate energies; Fusion excitation function; Vanishing of fusion

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