0000000000481809
AUTHOR
F. Bal
The NA48 event-building PC farm
The NA48 experiment at the CERN SPS aims to measure the parameter $\Re(\epsilon'/ \epsilon)$ of direct CP violation in the neutral kaon system with an accuracy of $2 \times 10^{-4}$. Based on the requirements of: \\\\ * high event rates (up to 10 kHz) with negligible dead time;\\ * support for a variety of detectors with very wide variation in the number of readout channels;\\ * data rates of up to 150 MByte/s sustained over the beam burst;\\ * level-3 filtering and remote data logging in the CERN computer center; \\\\ the collaboration has designed and built a modular pipelined data flow system with 40 MHz sampling rate. The architecture combines custom-designed components with commerciall…
A readout unit for high rate applications
The LHCb readout unit (RU) is a custom entry stage to the readout network of a data-acquisition or trigger system. It performs subevent building from multiple link inputs toward a readout network via a PCI network interface or alternatively toward a high-speed link, via an S-link interface. Incoming event fragments are derandomized, buffered and assembled into single subevents. This process is based on a low-overhead framing convention and matching of equal event numbers. Programmable logic is used both in the input and output stages of the RU module, which may be configured either as a data-link multiplexer or as entry stage to a readout or trigger network. All FPGAs are interconnected via…