HLT-TRD

Henner Büsching

Fast Track Closeout Meeting, June 07, 2004

Henner BueschingUniversity of Frankfurt

ALICE workshop Sibiu 08/22/08

• Providing ’physics’ trigger decisions

• Online event reconstruction and analysis

• Performance monitoring of the ALICE detectors

• Online production of calibration data

• Lossless compression of event data

High Level Trigger system

Event Selection relies on:– Processing in analysis steps

• Serial steps of feature extraction / hypothesis testing

• Modular analysis chain• Events can be rejected at any step if features do

not fulfil certain criteria (signatures)• Emphasis on early event rejectionEmphasis on early event rejection

– Reconstruction in Regions of Interest (RoIs)• RoI size/position derived from previous step(s)

High Level Trigger Strategy

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First steps to define triggers

• Jet Finder (TPC)– Fast seeded cone algorithm based on

charged tracks in TPC

• Single-electron (TRD)– improve statistics of open-charm and

open-beauty at ( pT > 1.5-2 GeV/c)

• Di-Muon trigger• Open charm• 0/ – gamma conversion

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Merge TPC -TRD tracking

ALICE High-Level Trigger

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Hardware Status

First year setup complete

• 87 Frontend PCs- 696 GB Memory- 348 CPU cores- 174 HLT Read-Out

Receiver Card- 348 DDL links

• 16 Infrastructure PCs • All Optical Fibers to DAQ

installed

Hardware Status

• GigaBit Ethernet network operational

• Interface nodes (2 each) to ALICE online systems- ECS / DCS / Offline

High Level Trigger system

DAQ HLT DCS Trigger

ECS

raw eventdata

analyzed events /trigger decisions

Mass Storage

• Dynamic software data transport framework (Publish-Subscriber)

• Cluster management (TaskManager)

• Analysis Software (AliRoot)

Software architecture

Components and the Chain

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Monitoring Scheme

Monitoring Scheme

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Monitoring

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Monitoring at CERN

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Status @ Time of Testbeam

ONLINE

•HLT-TRD monitoring was successfully running online in “test modus” at last beam time

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Status @ Time of Testbeam

ONLINE

Online Monitoring Tool

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Powerfull visualization tool for TRD exists(A.Bercuci)

Simple HLT online tool

Developed by RISEsummer studentKurt M. Barry

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Code consistency

• A strategic decision: Using offline code in HLT

• Pro:– Same results offline/online– Offline code well tested– Reliable usability for physics trigger decisions

• Con:– Potentially slow– Cumbersome optimization

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Getting ready for pp: Challenges

• Continuity– Guaranteeing operation in constantly

‘improving’ framework environment

• Stability– Fixing memory leaks

• Speed– Optimizing and speeding up routines

The Tracking Algorithm

clusters

Tracking Algorithm

4 seeding clusters

Tracking Algorithm

Riemann fit

Linear fit

Tracking Algorithm

2 cut: Finding real clusters around fit

Tracking Algorithm

tilted fits+ Kalman fits

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Summary

• ALICE HLT core system ready for data taking

• Online event reconstruction and analysis for TRD implemented

• Performance monitoring of TRD possible

• Running as it was designed to, but it now relies on the performance of the offline code.

• Task force working on ’physics’ trigger decisions

Sebastian Robert Bablok, Oystein Djuvsland, Kalliopi Kanaki, Joakim Nystrand, Matthias Richter, Dieter Roehrich, Kyrre Skjerdal, Kjetil Ullaland, Gaute Ovrebekk, Dag Larsen, Johan Alme

(University of Bergen, Norway)

Torsten Alt, Volker Lindenstruth, Timm M. Steinbeck, Jochen Thaeder, Udo Kebschull, Stefan Boettger, Sebastian Kalcher, Camilo Lara, Ralf Panse

(Ruprecht-Karls-University Heidelberg, Germany)

Konstantin Antipin, Harald Appelshäuser, Henner Büsching(University of Frankfurt, Germany)

Mateusz Ploskon(UC Berkeley, USA)

Haavard Helstrup, Kirstin F. Hetland, Oystein Haaland, Ketil Roed, Torstein Thingnaes( Bergen University College, Norway)

Kenneth Aamodt, Per Thomas Hille, Gunnar Lovhoiden, Bernhard Skaali, Trine Tveter(University of Oslo, Norway)

Indranil Das, Sukalyan Chattopadhyay (Saha Institute of Nuclear Physics, Kolkata, India)

Bruce Becker, Corrado Cicalo, Davide Marras, Sabyasachi Siddhanta(Cittadella Universitaria, Cagliari, Italy)

Jean Cleymans, Artur Szostak, Roger Fearick, Gareth de Vaux, Zeblon Vilakazi(University of Cape Town, South Africa)

Credits