Modeling event building architecture for the triggerless data acquisition system for PANDA experiment at the HESR facility at FAIR/GSI

Abstract

A novel architecture is being proposed for the data acquisition and trigger system of the PANDA experiment at the HESR facility at FAIR/GSI. The experiment will run without hardware trigger signal using timestamps to correlate detector data from a given time window. The broad physics program in combination with the high rate of 2 * 107 interactions per second requires very selective filtering algorithms accessing information from many detectors. Therefore the effective filtering will happen later than in today's systems ie. after the event building. To assess that, the complete architecture will be built of two stages: the data concentrator stage providing event building and the rate reduction stage. For the former stage, which requires a throughput of 100 GB/s to perform event building, we propose two layers of ATCA crates filled with Compute Nodes - modules designed at IHEP and University of Giessen for trigger and data acquisition systems. Currently each board is equipped with 5 Virtex4 FX60 FPGAs and high bandwidth connectivity is provided by 8 front panel RocketIO ports and 12 backplane ports for the inter-module communication.We designed simplified models of the components of the architecture and using the SystemC library as support for the discrete event simulations, demonstrate the expected throughput of the full-size system. We also show impact of some architectural choices and key parameters on the architecture's performance.