NUCFRG3: Light ion improvements to the nuclear fragmentation model

Light ion improvements to the nuclear fragmentation model, NUCFRG, are reported. Improvements include the replacement of the simple light ion production model with a light ion coalescence model and an improved electromagnetic dissociation (EMD) formalism. Prior versions of the model provide reasonable overall agreement with measured data; however, those versions lack a physics-based description for coalescence and EMD. The version reported herein, NUCFRG3, has improved the theoretical descriptions of these mechanisms and offers additional benefits, such as the capability to calculate EMD cross-sections for single deuteron, triton, helion, and alpha particle emission. NUCFRG3 model evaluation and validation show that the predictive capability has been improved and strengthened by the light ion physics-based changes. Based on increased capability and better theoretical grounding, it is recommended that NUCFRG3 replace its predecessors for space radiation assessments and other applications.