Progress in the Bunch-to-Bucket Transfer Implementation for FAIR

The transfer of bunched ion beams between various synchrotrons is required for the multi-accelerator complex FAIR, presently under construction at GSI. To avoid a dedicated distribution infrastructure for radiofrequency (RF) signals between each source and destination synchrotron, a new approach has been developed to transmit bunch and bucket phase information using synchronous Ethernet. This allows to locally regenerate all reference signals needed for the RF synchronization prior to a bunch-to-bucket transfer, as well as the triggers to the kickers. The modular and configurable hardware implementation based on the White Rabbit network progresses towards a proof-of-principle demonstrator. Besides the synchronization of revolution and RF frequencies, the bunches in the source accelerator must be aligned in azimuth with respect to the buckets in the receiving synchrotron. To validate the feasibility of this azimuthal steering, measurements have been performed with protons in the CERN PS to evaluate the longitudinal emittance growth. They are complemented with tracking simulations using the BLonD code.