Influence of nuclear de-excitation on observables relevant for space exploration

TL;DR

This paper demonstrates that the choice of nuclear de-excitation models significantly impacts the accuracy of space radiation environment predictions, often surpassing other sources of uncertainty in nuclear reaction simulations.

Contribution

It provides evidence that de-excitation models are a crucial and often underestimated source of uncertainty in nuclear reaction simulations for space applications.

Findings

De-excitation model choice affects key observables.

Systematic uncertainty from de-excitation can dominate total uncertainty.

Different model combinations yield varying predictions.

Abstract

The composition of the space radiation environment inside spacecrafts is modified by the interaction with shielding material, with equipment and even with the astronauts' bodies. Accurate quantitative estimates of the effects of nuclear reactions are necessary, for example, for dose estimation and prediction of single-event-upset rates. To this end, it is necessary to construct predictive models for nuclear reactions, which usually consist of an intranuclear-cascade or quantum-molecular-dynamics stage, followed by a nuclear-de-excitation stage. While it is generally acknowledged that it is necessary to accurately simulate the first reaction stage, transport-code users often neglect or underestimate the importance of the choice of the de-excitation code. The purpose of this work is to prove that the de-excitation model is in fact a non-negligible source of uncertainty for the prediction of several observables of crucial importance for space applications. For some particular observables, the systematic uncertainty due to the de-excitation model actually dominates the total uncertainty. Our point will be illustrated by making use of nucleon-nucleus calculations performed with several intranuclear-cascade/de-excitation models, such as the Li\`{e}ge Intranuclear Cascade model (INCL) and Isabel (for the cascade part) and ABLA07, Dresner, GEM, GEMINI++ and SMM (on the de-excitation side).