  We report on an experiment to produce a train of sub-picosecond microbunches
using a transverse-to-longitudinal emittance exchange technique. The generation
of a modulation on the longitudinal phase space is done by converting an
initial horizontal modulation produced using a multislits mask. The preliminary
experimental data clearly demonstrate the conversion process. To date only the
final energy modulation has been measured. However numerical simulations, in
qualitative agreement with the measurements, indicate that the conversion
process should also introduce a temporal modulation.
