Production of Energetic Light Fragments in Spallation Reactions

¹ Los Alamos National Laboratory, Los Alamos, NM 87545, USA
² University of Idaho, Moscow, Idaho 83844-4264, USA
³ Institute of Applied Physics, Academy of Science of Moldova, Chişinău, Moldova

^a e-mail: mashnik@lanl.gov

Published online: 20 March 2014

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 formany 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 Monte Carlo 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.