Prototype of White Rabbit Network in LHAASO

Synchronization is a crucial concern in distributed measurement and control systems. White Rabbit provides sub-nanosecond accuracy and picoseconds precision for large distributed systems. In the Large High Altitude Air Shower Observatory project, to guarantee the angular resolution of reconstructed air shower event, a 500 ps overall synchronization precision must be achieved among thousands of detectors. A small prototype built at Yangbajin, Tibet, China has been working well for a whole year. A portable calibration node directly synced with the grandmaster switch and a simple detectors stack named Telescope are used to verify the overall synchronization precision of the whole prototype. The preliminary experiment results show that the long term synchronization of the White-Rabbit network is promising and 500 ps overall synchronization precision is achievable with node by node calibration and temperature correction. INTRODUCTION The Large High Altitude Air Shower Observatory (LHAASO) project is a dedicated instrument for searching the origin of galactic cosmic rays, which consists of 4 sub-detector arrays. The 1km complex array (LHAASO-KM2A) includes 5635 scintillation electron detectors and 1221 muon detectors. 500 ps (rms) overall synchronization precision must be achieved among the spread thousands of detectors to guarantee the angular resolution of reconstructed air shower event. [1][2] A small prototype based on the White Rabbit (WR) network [3][4] is built at Yangbajin, Tibet, China on August, 2014. This paper talks about the deployment and synchronization monitor of the prototype.