Production of Energetic Light Fragments in Spallation Reactions

TL;DR

This paper extends nuclear reaction models to better predict the emission of energetic light fragments heavier than helium during spallation reactions, improving accuracy for applications like cosmic-ray studies and radiation therapy.

Contribution

The work introduces an extension to the preequilibrium model to include emission of fragments larger than 4He, enhancing the predictive capabilities of existing nuclear reaction models.

Findings

Improved agreement with experimental data for heavy light fragment emission.

Enhanced model accuracy across various target masses and energies.

Better prediction of high-energy tails for heavier light fragments.

Abstract

Different reaction mechanisms contribute to the production of light fragments (LF) from nuclear reactions. Available models cannot accurately predict emission of LF from arbitrary reactions. However, the emission of LF is important for many applications, such as cosmic-ray-induced single event upsets, radiation protection, and cancer therapy with proton and heavy-ion beams, to name just a few. The cascade-exciton model (CEM) and the Los Alamos version of the quark-gluon string model (LAQGSM), as implemented in the CEM03.03 and LAQGSM03.03 event generators used in the Los Alamos transport code MCNP6, describe quite well the spectra of fragments with sizes up to 4He across a broad range of target masses and incident energies. However, they do not predict high-energy tails for LF heavier than 4He. The standard versions of CEM and LAQGSM do not account for preequilibrium emission of LF larger than 4He. The aim of our work is to extend the preequilibrium model to include such processes. We do this by including the emission of fragments heavier than 4He at the preequilibrium stage, and using an improved version of the Fermi Break-up model, providing improved agreement with various experimental data.