Total reaction cross sections in CEM and MCNP6 at intermediate energies

Abstract

Accurate total reaction cross section models are important to achieving reliable predictions from spallation and transport codes. The latest version of the Cascade Exciton Model (CEM) as incorporated in the code CEM03.03, and the Monte Carlo N-Particle transport code (MCNP6), both developed at Los Alamos National Laboratory (LANL), each use such cross sections. Having accurate total reaction cross section models in the intermediate energy region (∼50 MeV to ∼5 GeV) is very important for different applications, including analysis of space environments, use in medical physics, and accelerator design, to name just a few. The current inverse cross sections used in the preequilibrium and evaporation stages of CEM are based on the Dostrovsky et al. model, published in 1959. Better cross section models are available now. Implementing better cross section models in CEM and MCNP6 should yield improved predictions for particle spectra and total production cross sections, among other results. Our current results indicate this is, in fact, the case.

Production of energetic light fragments in extensions of the CEM and LAQGSM event generators of the Monte Carlo transport code MCNP6

“…We conclude that the NASA approach is superior, in general, to the other available models (see Ref. [13,34,59,60] for the details of these findings). This is why we implement the NASA inverse cross sections into the MEM to be used at the preequilibrium stage of reactions.…”

“…A quite complete list of references on modern total-reaction-cross-section models, as well as on recent publications where these models are compared with each other and with available experimental data can be found in Ref. [34].…”

“…For these low-energy neutrons, we use the Kalbach systematics [57], which prove to be a very good approximation for the inverse cross sections of lowenergy neutrons, as discussed in Refs. [13,34,61]. In CEM03.03F, we use the Kalbach systematics [57] to replace the NASA inverse cross sections [55] for low-energy neutrons, similar to what was suggested and done in Ref.…”

“…Examples of inverse cross sections for the emission of neutrons together with discussions and relevant references can be found in Refs. [13,34,61]. We limit ourselves to one example with inverse cross sections for the emission of protons, and one example of inverse cross section for 12 C. Fig.…”

“…Many similar results for the emission of nucleons, complex particles, and LF heavier than 4 He can be found in Refs. [13,34,59,61].…”