大型放射光施設 SPring-8

問い合わせ番号

INS-0000000297

Bunch purity monitor

  When the SPring-8 storage ring is operated in the several-bunch or hybrid mode, some time-resolved experiments, which make use of the pulse characteristic of the synchrotron radiation, demand the bunch impurity of less than 10-9. The bunch impurity is defined as the ratio of the number of electrons in the unwanted bunch adjacent to the main bunch to that in the main bunch. It shows the quality of the pulse characteristic of the synchrotron radiation.
   In the SPring-8 storage ring, the bunch impurity has been measured by the gated photon counting system with fast light shutters in visible light region. The light shutters are normally closed, but applying the high voltage pulses opens them. By adjusting the operation timing of the shutters to the unwanted bunch before or behind the main bunch, we have accomplished the bunch impurity measurement with high sensitivity.