Multistep direct preequilibrium reactions and the Monte Carlo approach

We provide an overview of recent developments to the Hybrid Monte Carlo Simulation (HMS) model for calculating preequilibrium reactions. Illustrative examples are shown for nucleon and cluster induced reactions, and for assessing the importance of multiple preequilibrium processes. We present new results using HMS theory to study heavy nuclide recoil velocities, which are important in applications such as radiation heating, damage and single-event-upsets, and also discuss GNASH and TALYS code recoil predictions. We also discuss approaches for performing center-of-mass to laboratory kinematic transformations for the light-ejectile particles – we emphasize that correctly following the kinematics of sequentially decaying nuclei leads to results that can be quite different from those obtained using the traditional 2-body assumption for the recoil boost velocity. We also discuss how angular momentum transfer effects can be included semiclassically in the HMS model, allowing HMS to be linked to a Hauser-Feshbach code to study spin-dependent observables (such as gamma-ray, and isomer production).