Modeling Compound Nuclear Reactions with EMPIRE

Abstract

EMPIRE by Herman et al. (Nucl Data Sheets 108:2655, 2007) is a modular system of nuclear reaction codes, comprising various nuclear models, and designed for calculations over a broad range of energies and incident particles. A projectile can be a neutron, a proton, an ion, or a photon. The energy range extends from the beginning of the unresolved resonance region for neutron-induced reactions and goes up to several hundred MeV for heavy-ion induced reactions. The code accounts for the major nuclear reaction mechanisms, including direct, pre-equilibrium, and compound nucleus ones. Direct reactions are described by a generalized optical model or by a coupled channels approach. The pre-equilibrium mechanism can be treated by several quantum mechanical and semiclassical models. The compound nucleus decay is described by a full featured Hauser-Feshbach model with γ-cascade and width fluctuations. Advanced treatment of the fission channel takes into account transmission through a multiple-humped fission barrier with absorption in the wells. Here we will discuss the general capabilities of the code to model nuclear reactions and provide several examples of its use in modeling pre-compound and compound nuclear decay.