the atlas trigger configuration system design and commissioning a.dos anjos, p.bell, d.berge,...
DESCRIPTION
Thursday, September 6 The ATLAS Trigger Configuration System3 Trigger Design Fast, highly selective, efficient 40 MHz bunch crossing Hz storage rate ~40ms ~4sec ~3% of detector introduction to the ATLAS trigger in ATLAS HLT steering by S. George (Mo 16:50 Online Computing)TRANSCRIPT
The ATLAS TriggerConfiguration System
Design and CommissioningA.dos Anjos, P.Bell, D.Berge, J.Haller, S.Head, T.Kohno, S.Li, T.McMahon,
M.Nozicka, H.v.d. Schmitt, J.Stelzer, T.Wengler, W.Wiedenmann
Thursday, September 6 The ATLAS Trigger Configuration System 2
Outline
Trigger designConfigurable components
Configuration system requirementsData taking, MC production, offline analysis
Design and implementation
Commissioning status
Conclusions
Thursday, September 6 The ATLAS Trigger Configuration System 3
Trigger Design
Fast, highly selective, efficient
40 MHz bunch crossing
100-200 Hz storage rate
~40ms
~4sec
~3% of detector
introduction to the ATLAS trigger in ATLAS HLTsteering by S. George (Mo 16:50 Online Computing)
Thursday, September 6 The ATLAS Trigger Configuration System 4
Level 1 Trigger
Pre-processor
ClusterProcessor
Jet/EnergyProcessor
End-cap MuonTrigger (TGC)
Barrel MuonTrigger (RPC)
Muon-CTP-Interface (MuCTPI)
Central Trigger Processor (CTP)
LTP
BusyTTC
Detector Front-Ends/Read-out
LTP
BusyTTC
Muon DetectorsCalorimeter Detectors
Common Merger Modules
Trigger objects: Muons, EM and hadronic clusters, jets, total and missing ET
CTP
• Mapping of 480 hardware signals onto 160 CTP internal signals these signals encode the object multiplicities• Thresholds of trigger objects multiple thresholds for different object types• Item definitions: logic, prescale and veto rates maximum 256 trigger items• Random trigger rates, trigger on bunches or bunch groups
Configurable information on CTP:
Thursday, September 6 The ATLAS Trigger Configuration System 5
High Level Trigger (HLT)
Concept of trigger lines (chains)Chain: ordered list of trigger conditions (multiplicities of HLT trigger elements) to be evaluated in sequence)Description how algorithms produce trigger elements (example: L1EM3 ClusterFinder&Hypo L2_e5cl)Collection of chains (with prescale and forced-accept rates) HLT menu (see Teresa’s talk)
HLT algorithms configured through parametersSet via python (used in ATLAS as high level scripting language)
more details in talks about ATLAS HLT steeringby S. George (Mo 16:50 Online Computing)and about Trigger Reconstruction Algorithmsby T. Fonseca Martin (Mo 17:55 Online Computing)
signature (e j)
sequence (e) [EM “e-FEX, e-Hypo” e]
sequence (j) [JET “j-FEX, j-Hypo” j]
signature (e’ j’)
Chain (EJ-L2) input = “EMJET”
Chain (EJ-EF) input = “EJ-L2”
Lvl1 Trigger Item EMJET
y/n
y/n
y/n
y/n
L2EF
HLT Chain
Configurable information:• Chain definitions: logic (trigger conditions, algorithms), prescale and forced-accept rates maximum 8192 chains per menu• Algorithm parameters• Data streams, monitoring groups
Ste
erin
g, s
ee
Sim
on’s
talk
Thursday, September 6 The ATLAS Trigger Configuration System 6
Design Requirements for the Configuration System
Complete and consistent configuration of the ATLAS triggerOnline software and hardware for data takingTrigger simulation software in Monte Carlo production jobsConfiguration information provided to the user to perform trigger aware analyses and trigger studies
Flexible and fast configuration changes during data-taking to react to different beam and detector conditions
History of configurations for the purpose of understanding and reproduction of the trigger behavior
Thursday, September 6 The ATLAS Trigger Configuration System 7
Components of the Configuration System
Relational database stores trigger configuration (TriggerDB)
Trigger configuration via a single keyOffline reproducibilityTrigger historySchema reflects trigger design
Tool for database browsing and manipulation (TriggerTool)
Flexible and fast changes of the trigger during data takingTrigger experts, shift crew, offline analyst
Software clients to directly access the TriggerDB for
Data taking, simulation, and distribution of configuration data (conditions database)
TriggerDB
simulation production
shift crewoffline user expert
TriggerTool
Relational Access Layer
conditions database
datataking
Level 1 Menu + PrescalesHLT Menu + PrescalesAlgorithm parametersRelease version
TriggerDB Schema
Thursday, September 6 The ATLAS Trigger Configuration System 8
Operation of the Configuration System – Preparation
Level 1 TriggerMenu: stable in time, small changes to thresholds and trigger items by hand using TriggerTool
Trigger-Menu-Compiler creates image for Level 1 hardwarePrescales: adjusted by shifter to match the luminosity optimize bandwidth usage
High Level TriggerPrepare and validate trigger menu for data takingPopulate the TriggerDB with the HLT configuration information
Menu, algorithm parameters, prescale ratesCheck consistency with Level 1 configuration
Configuration alias for shifterLogical names (‘PHYSICS’, ‘COSMICS’, ‘CALIBRATION’) pointing to current valid configurations
ATLAS Trigger community responsible for the development and testing of the trigger algorithms to achieve the ATLAS physics goals
Thursday, September 6 The ATLAS Trigger Configuration System 9
TriggerDB during Data Taking
Shifter to chose trigger configuration alias before CONFIG transitionConfiguration key written to online configuration database to be picked up by Level 1 CTP controller and HLT processes
At CONFIG: CTP controller loads image from TriggerDB into the CTP hardwareHLT processes load configuration from TriggerDB into memory and initialize themselves
At START run: partial configuration information is written into the ATLAS conditions database (COOL) as run-wise trigger configuration data
While RUNNING:Level 1 prescales can change written to COOL Trigger Panel in the ATLAS Run Control interface
see talk about ATLAS Online Configuration Database by I. Soloviev
(Wed 15:05 Online Computing)
Thursday, September 6 The ATLAS Trigger Configuration System 10
Trigger Result
Run-wise configuration data to interpret trigger decision (conditions database)
Event wise trigger decision encoded in the bytestream
Maps: trigger names to bit position and chain counterAllows for access to the trigger decision using trigger names
Information about trigger definition at each step of chain-processingTo rebuild the HLT menu and access the trigger objects by name
Prescale, LVL1 veto and HLT forced accept rates and trigger chains
Level 1 trigger: Acceptance flags for the up to 256 active trigger items before and after the application of prescale and veto 3 x 256 bitsHigh level trigger: Acceptance flags for each chain before and after the application of prescale and forced-accept
Chains are identified by a short integer (chain counter)Index of last successfully processed step for each chainTrigger objects e.g. hadronic clusters, muon tracks
Information to link these HLT trigger objects to the Level 1 trigger objects (trigger studies)
Thursday, September 6 The ATLAS Trigger Configuration System 11
ES
D 1
00M
B/s
AO
D 2
0MB
/s
ESDAOD
TAG files/DB
Flow of Configuration DataMore details in talk about ATLAS Databases
by A. Vaniachine (Wed 14:40 Distributed data analysis) and about ATLAS Tag DB
by F. Viegas (Wed 14:40 Software Components)
L1Result
to
Tier0
express calib
Tier
1
tran
sfer
Tier 0
Prompt Reconstruction
Express Reconstruction,
calibration
Tier 1 Reprocessin
gTier 2MC
production
ConditionsDatabase
Trig
ger
Men
us
into
Con
ditio
ns D
B
ConditionsDatabase
TriggerDB
DbProxy
LVL2 Result
EFResult
RODs
Front-end
LVL2
Subfarm Input
EF EF EF
Event Builder
LVL1/CTP
Subfarm Output
EF
Trigger ResultTrigger Objects
1. TriggerDB to configure trigger for data taking
2. Configuration data to COOL
3. Trigger result in each event
4. Shipped to reconstruct-ion sites
5. ESD, AOD, TAG for trigger aware analysis TriggerDB
Replication
Thursday, September 6 The ATLAS Trigger Configuration System 12
Trigger Information for trigger studies and physics analysis
Configuration Data in Offline Analysis
TriggerDBAll configuration data
online DB (COOL)
• Configuration: Lvl1 items and HLT chains (name, version), prescale-, Lvl1 veto- and HLT pass-through rates• Trigger result: pass or fail? reason: prescaled, vetoed, pass-through? last successful step in each chain?• Navigation: which trigger object caused the trigger decision ?• Trigger Event Data: rerun the trigger selection offline with tightened criteria
Encoded trigger decision
Decodedtrigger menu
Persistence
ESDEvent Summary Data
AODAnalysis Object Data
Decoded Trigger Menu
Configuresfor Datataking
Trigger Information(transient)
Transient
Thursday, September 6 The ATLAS Trigger Configuration System 13
Analysis and Trigger Studies
Common: check if event passed a desired triggerTrigger efficiency, luminosity calculations (on TAG DB)
Navigate to trigger object that caused trigger-acceptZee trigger + single electron trigger to study electron trigger efficiency
Rerunning the trigger without reconstruction of trigger objectsRun trigger as during data taking, but switch off trigger feature extraction (FEX) algorithms (see Simon’s talk)Perform selection with tighter requirements (HYPO algorithms)Turn on curves, …
Most trigger analyses possible on AOD data!
Thursday, September 6 The ATLAS Trigger Configuration System 14
Interaction with the TriggerDB – TriggerTool
Integrated consistency
checking
Tree view for trigger menus(and subsets) Table view for plain data
Simple and advanced search capabilities
Shifter ModeChange prescale factors or trigger menu to react on changing detector or beam conditions
User ModeBrowse: trigger menus, detailed information like algorithm parameters
Expert modeUpload new and manipulate existing configurations
Intuitive JAVA based GUI to browse andmanipulate trigger configurations
Search results
Edit pane (e.g. for chains)
Thursday, September 6 The ATLAS Trigger Configuration System 15
Commissioning LVL1 Configuration
ATLAS Central Trigger Processor (CTP) tested for over a 1 year on cosmic data using input from various detector sub-systems
See also Commissioning the ATLAS trigger by J. Boyd (Wed 17:30 Online Computing)
Cosmic-ray RPC impact points, extrapolated to ground level
ATLAS access shafts
Complete muon cosmic ray slice LVL1 + LVL2 in February 2007
Muon trigger LVL1 provides trigger and seed for LVL2 LVL2 algorithm requests detector data to reconstruct muon candidates
Configuration of CTP from the TriggerDB is default
August commissioning week:Writing of LVL1 trigger configuration to conditions database for each run
Thursday, September 6 The ATLAS Trigger Configuration System 16
Commissioning HLT Configuration
Large Scale Tests in December 2006Simple trigger setup, large computing farm: 600 dual core processorsTriggerDB access via the ATLAS DbProxy – service that caches database requests and replies to reduce load on primary database
Two following technical runs in March and May 2007 on simulated and cosmic data
Small computing farm (part of the final ATLAS trigger farm)Test of complex trigger menusExercising the TriggerTool in a shift-like environment
August commissioning week:Tested writing of HLT configuration to conditions database for each run
ATLAS Run Control interface during LST
Thursday, September 6 The ATLAS Trigger Configuration System 17
Trigger Configuration for Simulation Production
AdvantagesConsistency between online trigger and simulation
Configurations created and used during data taking can easily be used in MC production
More flexible propagation of configuration changes to MC production sites
Currently a new MC production cycle requires a new software releaseCan be replaced by software release + configuration key faster turn around if only trigger menus or algorithm parameters need adjustment
System under construction
TriggerDB holds complete trigger configuration can be used to simulate the trigger in the exact same way as it is configured for data taking
Thursday, September 6 The ATLAS Trigger Configuration System 18
Summary
System designed and implemented to provide consistent configuration of all three trigger levels
Access to trigger configuration consistently for data taking, Monte Carlo production, and trigger studies / trigger aware analysis
Fast and flexible response to changing detector or beam conditions during data taking
System provides a trigger history over the ATLAS lifetime, easily accessible by the analyst using the TriggerTool
Commissioning of the system for Level 1 and HLT separately and combined during cosmic test runs and large scale farm tests