Measurement of bunch time-structure in KEK PF

The time-structure of the bunches in the KEK-PF storage ring under the single bunch condition was measured by means of a photon counting system installed in beamline 21. When the jitter in the electronic system is negligible, the response of the whole system is finally determined by a transit time spread (TTS) of a photomultiplier (PMT). The TTS of the PMT was measured with a picosecond pulse laser system, pulse width of which was about 7 ps in FWHM. A current dependence of the longitudinal bunch shape was observed with the improved system and was found the increase of the asymmetry with the increase of the current.<>