Bochum 2009 – scientific programme

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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.