OPTFRAG: An Optical Model Code for Predicting Nuclide Production from Heavy Ion Fragmentation

摘要

Methods of accurately and rapidly estimating secondary particle production yields from nucleon-nucleus and nucleus-nucleus collisions in thin and thick targets are needed for a variety of applications including the production of radioactive beams, space radiation shielding for interplanetary missions, and heavy ion radiotherapy. Recently the Monte Carlo radiation transport code HETC has been extended to include the transport of heavy ions for space radiation shielding applications. A critical element of this extension of the code was the development of the initial high-energy heavy ion event generator, which is needed to describe the nuclear interactions of the incident heavy ions and the production of their secondary particles in the collisions. Included in these secondary particles are all nuclear species lighter than the incident projectile nucleus, neutrons, and mesons. The present event generator does not yet include mesons from nucleus-nucleus collisions. The nuclear fragmentation model incorporated in the HETC event generator is the NUCFRG2 model developed at NASA Langley Research Center. NUCFRG2 is also currently used in the deterministic space radiation transport code HZETRN, also developed at NASA Langley. The NUCFRG2 model is a knockout - ablation (abrasion-ablation) model based upon a classical collision description that treats the colliding nuclei as opaque spheres. Cross sections are determined from geometry considerations that do not account for quantum scattering effects in the collisions and do not include the actual density distributions of the colliding nuclei.