A New Code System for the Calculation of Double Differential Reaction Cross Sections

Abstract The statistical exciton model following the master-equation approach has been improved and extended for application as an evaluation tool of double-differential reaction cross sections at incident nucleon energies of 5 to 50 MeV. For this purpose the code system GRAPE, centered around the exciton-model code GRYPHON has been developed, which combines a number of interesting features such as: unified treatment of pre-equilibrium and equilibrium processes, renormalized exciton state-densities summing up to the back-shifted Fermi gas formula, a new model for the internal transition rates based upon the nucleon mean free path in nuclear matter, angle-energy distributions based on intra-nuclear scattering in nuclear matter, account of discrete-level excitations, a new model for γ-ray competition, inclusion of multi-particle emission, and various sorting options with code output in the new ENDF-VI format. A major characteristic of the proposed model is that consistency with equilibrium models has been i...

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