Fibre channel based event builder and network for the Euroball experiment

The Euroball experiment is an European project aiming to build a very sensitive 4/spl pi/ gamma spectrometer based on HpGe crystals. The spectrometer is very efficient and the foreseen trigger rate ranges from 40 KHz to 100 KHz with a total bandwidth of 30 MByte/s. The paper presents the data acquisition system of the experiment focusing the discussion on the selected event builder architecture: a very fast switching network based on the Fibre Channel Standard (FCS). The behaviour of the system and in particular of the FCS switch has been validated by means a simulated model describing the main features of the architecture. Test benches performed with the FCS switches of two different vendors and several FCS nodes (workstations, VME adapters, etc.) are presented. Point to point performances, round trip time, switch latency and switch latency against switch loading are the main parameters measured.