BUNCH LENGTH MEASUREMENTS ON CLIO

The lengths of both electron and laser micropulses have been measured under various conditions. The width of the electron bunches varies between 8 and 16 ps FWHM for standard operation of the linac in our usual 32-50 MeV range. The laser micropulse length varies between 1.5 and 6 ps at 8 mum, depending on the detuning of the optical cavity length. Shorter pulses of subpicosecond duration have been produced by running our linear accelerator in a configuration where the electron bunches acquire a quasi-linear time-energy relationship while travelling on the side, rather than on the crest, of the accelerating high-frequency wave.