2. Synchronization

Abstract

To realize the bucket-to-bucket transfer from the 3-GeV RCS and 50-GeV MR, a synchronization system, which couples the RF control systems of two synchrotrons, is necessary. Also, the neutron chopper requires precise timing. We focus on the RCS-MR synchronization here. MR RF RCS RF phase / tag info. RCS MR Figure 3.5.1 Schematic diagram of the RCS-MR synchronization Figure 3.5.1 shows a schematic of the coupling of two synchrotrons. In the injection period of the MR, the RF system provides RF signals of a fixed frequency. The information sent from the MR to the RCS is following; (1) phase of the DDS signals in the MR RF system, (2) a "tag" which identifies the proper empty bucket. The positions of bunches in the RCS are controlled during acceleration by using the phase information from MR so that two bunches are in the proper phase at the top energy. The tag information gives the proper timing for triggering the kickers at the time of the empty buckets in the MR. At the top energy of the RCS, the RF frequencies of the RCS and the MR are same. Also, the harmonic numbers of the RCS and the MR are 2 and 9, respectively. This means that every four and a half turns of the RCS there is a chance to fire the kickers. One should notice the following points; The RCS has no flattop. Also, at the extraction the RF frequencies of the RCS and the MR are same; we cannot use the beat-method at the flattop The frequency of the synchrotron oscillation of the RCS is slow. It varies from several kHz (during the acceleration) to 400 Hz (near the extraction). Hence, the bunches move slowly with changing the RF phase or frequency near the extraction