Heidelberg 2015 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 41: Instrumentation 13

HK 41.7: Talk

Wednesday, March 25, 2015, 16:15–16:30, M/HS1

A FPGA based DAQ for the COMPASS experiment — •Stefan Huber — Technische Universiät München

In this contribution the deployment and first results of the new FPGA-based data acquistion system (DAQ) of the COMPASS experiment is presented. Since 2002, number of channels increased from 190000 to approximately 300000, trigger rate increase from 5 kHz to 30 kHz; the average event size remained roughly 35 kB. In order to handle the increased data rates, it has been decided to develop a new DAQ system during technical shutdown of CERN accelarator in 2013-2014. The new system replaces the old computer based event building network with custom FPGA based data handling cards (DHC). The DHC cards use two different versions of firmware: multiplexer and switch. The multiplexer card can combine 15 incoming links into one outgoing, whereas the switch combines 8 data streams from multiplexers and using information from look-up table sends the full events to the readout engine servers equipped by spillbuffer PCI-Express cards that receive the data. Both types of DHC cards can buffer data which allows to distribute the load over the cycle of accelerator. As the DHC cards perform data flow control and event building, the software serves only for configuration, run control, and monitoring. For these purposes, we have developed software tools. The new DAQ system has been deployed for the pilot run starting from the September 2014. In the paper, we present preliminary performance and stability results of the new DAQ, we compare it with the original system in more detail.