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HK: Fachverband Hadronen und Kerne
HK 53: Accelerators and Instrumentation II
HK 53.1: Talk
Wednesday, March 18, 2009, 14:00–14:15, H-ZO 90
Trigger Schemes of the ALICE TRD Global Tracking Unit — •Felix Rettig — Kirchhoff Institute for Physics, University of Heidelberg
The Transition Radiation Detector of the ALICE experiment
is designed to provide a fast Level-1 trigger for
different classes of signatures as well as full event information for offline reconstruction.
A total of 1.2 million analog channels is processed massively parallel in a two-stage
approach to derive a trigger decision within 6 µs after the interaction.
Pattern matching algorithms
are employed in 65 000 FEE Multi-Chip Modules to
parametrize up to 20 000 stiff track segments.
The detector data is then transferred to the second stage,
the Global Tracking Unit (GTU), via 1 080 optical fibres at an
aggregate bandwidth of 2.7 TBit/s.
The GTU itself consists of 109 dedicated FPGA-based processing nodes
forming a three-level hierachy. 90 Track Matching Units perform
online 3D track reconstruction and momentum calculation within 1.2µs.
Full track and momentum information of azimutal detector segments
is then forwarded to one of the 18 Supermodule Units for trigger pre-computation.
The top-level Trigger Generation Unit finally computes the overall
TRD trigger decision.
This talk focuses on the current status of the GTU and
the GTU-based cosmic trigger used for ALICE data taking and
supermodule production during 2008.
Developments for future trigger schemes in p-p operation,
especially for specific decays (J/ψ, Y) involving online
invariant-mass calculations as well as for jets, will be presented.