Evaluation of ultrashort electron pulse shape via radiation measurement

Recent advanced electron linear accelerators can produce a subpicosecond relativistic electron pulse, which are going to be applied to pulseradiolysis analysis for radiation chemistry and physics and free electron laser etc. There are two major methodologies to evaluate the subpicosecond electron pulse, which are the femtosecond streak camera measurement via Cherenkov radiation and coherent far infrared transition radiation interferometry. Both measurements have been carried out and comparied with each other at the S-band twin linear accelerators of Nuclear Engineering Research Laboratory, University of Tokyo. The theory, results, precision and problems are reviewed here. (author)