The CMS Trigger Group of the Institute for High Energy Physics in Vienna (HEPHY) is involved in the design of the level-1 trigger of the CMS experiment at CERN. At the Large Hadron Collider (LHC) 40 million collisions of proton bunches occur each second, resulting in about 800 million proton collisions. The trigger system serves to select only those that are interesting for exploring expected and unexpected new physics processes at high energies. The level-1 trigger, a custom designed electronics system, performs a quick on-line analysis of each collision, every 25 nanoseconds, and decides whether to reject or to accept it for further analysis by the high-level trigger implemented in a computer farm. The output event rate of the level-1 trigger is at most 100 000 per second. The high-level trigger reduces this rate to a few hundred collisions per second, which are stored for off-line analysis.
Without the trigger electronics developed by our group not a single event could be recorded in CMS nor could any detector be read out!
Trigger Group Responsibilities
The Drift Tube Track Finder reconstructs muon tracks from track segments measured in the drift tube muon chambers. The Global Muon Trigger compares muon candidates from all muon detectors, eliminates fake muons, and optimizes geometrical acceptance. The Global Trigger takes the decision to accept or reject an event. The Central Trigger Control System electronically controls the data taking. The Trigger Supervisor software system controls and coordinates all trigger systems.
The Global Trigger, the Global Muon Trigger and the central Trigger Control System were entirely developed and built by our group, in collaboration with the Electronics 1 department. The major part of the Drift Tube Track Finder was also developed and produced by the group. The Autonomous University of Madrid and INFN Bologna also made contributions. The Trigger Supervisor was proposed by our group and we also developed its base version. Further developments are made in collaboration mainly with CERN.
For members and contact details see group members.