Synchronizing the different parts of a Particle Physics detector is an essential part of its operation. We describe the system being planned for the DUNE liquid argon neutrino detector and experience from the single phase protoDUNE detector currently operating at CERN.
DUNE is will have four caverns, each of which can house a detector with 10kT fiducial mass. The first caverns is planned to house a single phase module and the second a dual phase module. In both systems the time-stamps are locked to timing provided by GPS/GLONASS antennae.
Due to the different readout architectures of the single phase dual phase different timing distribution methods are used: The dual phase module will use IEEE1588 (White Rabbit). The single phase will use a simpler protocol designed to be easy to implement in the readout elements receiving timing and clock.
The timing distribution system for the single phase detectors can use passive optical fan-outs which reduces cost and allows for the use of redundant timing masters.
Measurements on the single phase protoDUNE system indicate that the timing distribution system adds ~ 15ps RMS per hop.
We describe the measures taken to reduce the risk of “silent failures” where synchronisation is lost with GPS without being detected. This is achieved using separate, spatially separated, antennae together with independent GPS receivers.