  An improved version of the Cascade-Exciton Model (CEM) of nuclear reactions
implemented in the codes CEM2k and the Los Alamos version of the Quark-Gluon
String Model (LAQGSM) has been developed recently at LANL to describe reactions
induced by particles and nuclei at energies up to hundreds of GeV/nucleon for a
number of applications. We present several improvements to the intranuclear
cascade models used in CEM2k and LAQGSM developed recently to better describe
the physics of nuclear reactions. First, we incorporate the photonuclear mode
from CEM2k into LAQGSM to allow it to describe photonuclear reactions, not
previously modeled there. Then, we develop new approximations to describe more
accurately experimental elementary energy and angular distributions of
secondary particles from hadron-hadron and photon-hadron interactions using
available data and approximations published by other authors. Finally, to
consider reactions involving very highly excited nuclei (E* > 2-3 MeV/A), we
have incorporated into CEM2k and LAQGSM the Statistical Multifragmentation
Model (SMM), as a possible reaction mechanism occurring after the
preequilibrium stage. A number of other refinements to our codes developed
recently are also listed.

Nuclear Theory;Astrophysics;Nuclear Experiment