Synchronization system between two master oscillators of SACLA and SPring-8 storage ring 2

Preparation of a timing system to inject a beam from a linac of SACLA to the Storage Ring (SR) of SPring-8 is underway. One of the challenges is to synchronize two accelerators without degrading the performance of the XFEL operation of SACLA. We tested a prototype of a synchronization system by adjusting the timing of the master trigger signal of SACLA to the revolution timing of SR, and by applying FM modulation to the master oscillator of SACLA. We succeeded in synchronizing the timing between two signals (a 79 MHz signal which is one-third of 238 MHz of SACLA's timing reference frequency, and an 85 MHz signal which is one-sixth of 508.58MHz of SR's one) within 1.2 ps rms. But we also observed a phase slip in a PLL circuit of a laser used at pump and probe experiments at SACLA. A counter measure was tested which utilized that the timing of the 79 MHz signal relative to the 85 MHz signal changes -0.1 ns after one revolution period of the SR. The timing difference was minimized from 12 ns to 0.1 ns by waiting appropriate revolution count before generating the master trigger signal. On the other hand, this timing delay caused the deviation of the master trigger signal from the AC 60 Hz zero crossing timing, which lead to the beam kick by the heater current of the electron gun. We measured the effect of this timing deviation on the beam position and angle. We found the deviations were less than 3 μm and 0.2 μrad with a 0.2 ms delay from zero-cross timing, which were acceptable level. The injection test from SACLA to SR will be started in 2018 fiscal year. (author)