Beam-phase measurement system for HIRFL

The beam phase measurement system in HIRFL is introduced. The system had been improved using RF-signal mixing and filtering techniques and noise cancellation method. Therefore, the influence of strongly RF disturbing was eliminated and the signal to noise rate was increased, and a stable and sensitive phase measurement system was developed. The phase history of the ion beam was detected by using 15 sets of capacitive pick-up probes installed in the SSC cyclotron. The beam phase information was necessary for tuning purposes to obtain an optimized isochronous magnetic field, where the beam intensity was increased and the beam quality was optimized. The measurement results before and after optimized isochronous magnetic field for 40Ar15+ ion and 12C6+ ion in SSC were given. The phase measurement system was reliable by optimizing isochronous magnetic field test, and the precision reached ±0.5°, the sensitivity of beam signal measurement was about 10nA as well.