  Commissioning at the SCRF accelerator at the Fermilab Accelerator Science and
Technology (FAST) Facility has included the implementation of a versatile
bunch-length monitor located after the 4-dipole chicane bunch compressor for
electron beam energies of 20-50 MeV and integrated charges in excess of 10 nC.
The team has initially used a Hamamatsu C5680 synchroscan streak camera to
assess the effects of space charge on the electron beam bunch lengths. An
Al-coated Si screen was used to generate optical transition radiation (OTR)
resulting from the beam's interaction with the screen. The chicane bypass
beamline allowed the measurements of the bunch length without the compression
stage at the downstream beamline location using OTR and the streak camera. We
have observed electron beam bunch lengths from 5 to 16 ps (sigma) for
micropulse charges of 60 pC to 800 pC, respectively. We also report a
compressed sub-ps micropulse case.
