SODA: Time distribution system for the PANDA experiment

The PANDA data acquisition system will operate in trigger-less mode and collect about 100 GBytes of data per second from more than a thousand front-end modules. The information from all detectors is combined into data blocks, every block corresponds to 500 microseconds of beam. The SODA (Synchronization Of Data Acquisition) project aims to develop a versatile optical network system which is, first of all, able to provide a common reference time with a precision better than 20 ps R.M.S. In addition, the system synchronizes data taking with the burst structure and performs monitoring of data acquisition modules. Furthermore, it takes responsibility for data flow control. The core of the system is a point-to-multipoint bidirectional optical link which is able to broadcast information from a master module to few hundred destinations and to acquire information from the destination modules via a passive optical fiber network. The first prototype system has been built and tested. The architecture of the SODA system, the hardware implementation and the performance parameters of the prototype system are discussed.