Performance test and initial application of White Rabbit system at SuperKEKB

The basic performance of the White Rabbit system is studied at KEK. The precision in the timestamp synchronization and the timing-trigger delivery is measured with the direct connection of two White Rabbit modules. The long-term stability of the timestamp synchronization is measured with the one master and two slave nodes configuration. The jitter of the PPS signals from two slave modules is 63.46 ps and stable for more than one week. This stable synchronization is realized by automatically measuring and calibrating the cable delay in every second. The initial application to the SuperKEKB operation is carried out in the 2020 spring run. The latency of the Abort Trigger System is measured with the common timestamp of the White Rabbit system. We configure the White Rabbit system for synchronizing its common timestamp with that of the Event Timing System. The common timestamp will be an important technology in the future SuperKEKB operation. (author)