NOvA DAQ, System Architecture, Data Combiner and Timing System

NOnuA (E929) is a long baseline experiment that will search for neutrino oscillations. There will be one detector near the beam source at Fermilab, and one detector in northern Minnesota. The DAQ system for the far detector collects over-threshold hits from over 450,000 channels of scintillator readouts, sorts the time-stamped data packets and archives selected time periods of data for transmission and processing. While a simple point-to-point protocol is used for the first level of data collection, Ethernet was chosen as the fabric for the rest of the DAQ. The packet time-stamp and overall system synchronization is based on two common-view GPS trained clock oscillators, one at each site. The present design cost-effectively satisfies the experiment's moderate speed and data volume requirements.