Longitudinal Electron Bunch Diagnostics Using Coherent Transition Radiation

The longitudinal charge distribution of electron bunches in the Fermilab/Nicadd A0 photoinjector was determined using the coherent transition radiation produced by electrons passing through a thin metallic foil. The autocorrelation of the transition radiation signal was measured with a Michelson-type interferometer. The response function of the interferometer was determined from measured and simulated power spectra for low electron bunch charge and maximum longitudinal compression. A Kramers-Kronig technique was used to determine longitudinal charge distribution. Measurements were performed for electron bunch lengths in the range from 0.3 to 2 ps (rms).