  Here we report on a particular type of RPC that presents up to 99% efficiency
for minimum ionizing particles and a very sharp time resolution, below 50 ps
sigma in the most optimized conditions. Our 9 cm2 cells, made with glass and
metal electrodes that form accurately spaced gaps of a few hundred micrometers,
are operated at atmospheric pressure in non-flammable gases and can be
economically produced in large quantities, opening perspectives for the
construction of large area time of flight systems.
