  We present a Monte Carlo implementation, within PYTHIA, of medium-induced
gluon radiation in the final state branching process. Medium effects are
introduced through an additive term in the splitting functions computed in the
multiple-soft scattering approximation. The observable effects of this
modification are studied for different quantities as fragmentation functions
and the hump-backed plateau, and transverse momentum and angular distributions.
The anticipated increase of intra-jet multiplicities, energy loss of the
leading particle and jet broadening are observed as well as modifications of
naive expectations based solely on analytical calculations. This shows the
adequacy of a Monte Carlo simulator for jet analyses. Effects of hadronization
are found to wash out medium effects in the soft region, while the main
features remain. To show the performance of the implementation and the
feasibility of our approach in realistic experimental situations we provide
some examples: fragmentation functions, nuclear suppression factors, jet shapes
and jet multiplicities. The package containing the modified routines is
available for public use. This code, which is not an official PYTHIA release,
is called Q-PYTHIA. We also include a short manual to perform the simulations
of jet quenching.
