Münster 2011 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 22: Schwerionenkollisionen und QCD Phasen IV
HK 22.8: Vortrag
Dienstag, 22. März 2011, 18:30–18:45, HS AP
ALICE TRD GTU Online Tracking and Trigger Performance in pp and PbPb Collisions — •Felix Rettig, Stefan Kirsch, and Volker Lindenstruth — Frankfurt Institute for Advanced Studies, University of Frankfurt
The ALICE Transition Radiation Detector is designed to provide fast trigger contributions for several signature classes. A total of 1.2 million analog channels is preprocessed massively parallel by more than 65000 custom quad-processor multi-chip modules. By means of pattern matching algorithms, short stiff track segments are identified and parametrized. Within 3µs up to several thousand track segments per event are then transferred to a second stage, the Global Tracking Unit.
The GTU consists of 109 FPGA-based processing nodes arranged in a three-level hierarchy, where 90 nodes receive track segment data at an aggregate bandwidth of up to 2.16 TBit/s and perform an online 3D reconstruction and momentum calculation for high-momentum tracks within 1.2µs. Track information is forwarded to 18 Supermodule Units running local trigger algorithms, i.e. a single high-momentum electron trigger and a jet trigger. The top-level Trigger Generation Unit provides the TRD global trigger contributions to the central ALICE trigger system within 6µs after the collision.
Presented here is the performance of the online tracking and selected triggers based on the first year of LHC operation with pp collisions at √s ≤ 7 TeV as well as PbPb collisions at √sNN=2.76 TeV.