M. Nakamura, M. Takanaka, S. Okuda, T. Kozawa, R. Kato, T. Takahashi* and S. Nam**
ISIR, Osaka University, *Research Reactor Institute, Kyoto University, **Department of Physics, Kangwon National University
Single-bunch electron beams generated with the 38 MeV L-band linear accelerator are being used for experiments of the self-amplified spontaneous emission and the coherent radiation at the Institute of Scientific and Industrial Research in Osaka University. The spectrum of the coherent radiation emitted from an electron bunch is determined by the bunch shape. In this work, the bunch shape was evaluated from the longitudinal bunch form factor which was given by the spectrum of the coherent transition radiation measured with a Martin-Pupplet interferometer in a wavenumber range of 2-25 cm-1. A streak measurement at a time resolution of 0.9 ps was also performed in the same configurations. The energy of the electron beam used in the experiments was 27 MeV, the energy spread 1.1% FWHM, and the electron charge in a bunch 13.5 nC. The bunch length was found to be 29 ps FWHM by the streak measurement. The longitudinal bunch form factor obtained by the measurement agreed with that for the triangular bunch shape at the same bunch length. By using a chicane-type bunch compressor the decrease of bunch length to 18 ps FWHM was observed.
