Measurement of an electron bunch shape using coherent radiation. Construction of a Martin-Puplett type interferometer

Coherent radiation was observed first in the world in 1989 by using 300 MeV Linac of the Laboratory of Nuclear Science, Tohoku University. Since then, it was also observed by using the other electron Linac, and its study has been conducted. As its spectra contains bunch-like information, it can be used for measurement of bunch shape. For measuring method of the bunch shape, there are some methods using streak photographing camera, beam forming lights such as transition radiation, Cerenkov radiation, synchrotron radiation and so forth, out of which the methods except the synchrotron radiation have possibility of the beam breakdown. In this study, in order to measure the bunch shape using the coherent radiation, a Martin-Puplett type interferometer was prepared to conduct a calibrated experiment due to high pressure mercury-vapor lamp. The interferometer test was conducted on a specimen with 20 micrometer in sampling width and 25 mm in movable mirror movement. For this interferogram, spectrum was calculated by using high speed Fourier transfer using Sande-Tukey algorithm. (G.K.)