  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.
