  The interaction of a high-current $O$(100~\textmu A), medium energy
$O$(10\,GeV) electron beam with a thick target $O$(1m) produces an overwhelming
shower of standard matter particles in addition to hypothetical Light Dark
Matter particles. While most of the radiation (gamma, electron/positron, and
neutron) is contained in the thick target, deep penetrating particles (muons,
neutrinos, and light dark matter particles) propagate over a long distance,
producing high-intense secondary beams. Using sophisticated Monte Carlo
simulations based on FLUKA and GEANT4, we explored the characteristics of
secondary muons and neutrinos and (hypothetical) dark scalar particles produced
by the interaction of Jefferson Lab 11 GeV intense electron beam with the
experimental Hall-A beam dump. Considering the possible beam energy upgrade,
this study was repeated for a 20 GeV CEBAF beam.
