The ATLAS Trigger Configuration System Design and Commissioning A.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 System2 Outline Trigger design Configurable components Configuration system requirements Data taking, MC production, offline analysis Design and implementation Commissioning status Conclusions

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)

Thursday, September 6 The ATLAS Trigger Configuration System4 Level 1 Trigger Pre-processor Cluster Processor Jet/Energy Processor End-cap Muon Trigger (TGC) Barrel Muon Trigger (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 E T 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 System5 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 parameters Set via python (used in ATLAS as high level scripting language) more details in talks about ATLAS HLT steering by S. George (Mo 16:50 Online Computing) and about Trigger Reconstruction Algorithms by 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 L2 EF 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 Steering, see Simon’s talk

Thursday, September 6 The ATLAS Trigger Configuration System6 Design Requirements for the Configuration System Complete and consistent configuration of the ATLAS trigger Online software and hardware for data taking Trigger simulation software in Monte Carlo production jobs Configuration 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 System7 Components of the Configuration System Relational database stores trigger configuration (TriggerDB) Trigger configuration via a single key Offline reproducibility Trigger history Schema reflects trigger design Tool for database browsing and manipulation (TriggerTool) Flexible and fast changes of the trigger during data taking Trigger 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 userexpert TriggerTool Relational Access Layer conditions database data taking Level 1 Menu + Prescales HLT Menu + Prescales Algorithm parameters Release version TriggerDB Schema

Thursday, September 6 The ATLAS Trigger Configuration System8 Operation of the Configuration System – Preparation Level 1 Trigger Menu: stable in time, small changes to thresholds and trigger items by hand using TriggerTool Trigger-Menu-Compiler creates image for Level 1 hardware Prescales: adjusted by shifter to match the luminosity  optimize bandwidth usage High Level Trigger Prepare and validate trigger menu for data taking Populate the TriggerDB with the HLT configuration information Menu, algorithm parameters, prescale rates Check consistency with Level 1 configuration Configuration alias for shifter Logical 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 System9 TriggerDB during Data Taking Shifter to chose trigger configuration alias before CONFIG transition Configuration 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 hardware HLT 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 System10 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 counter Allows for access to the trigger decision using trigger names Information about trigger definition at each step of chain-processing To 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 bits High 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 chain Trigger 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 System11 ESD 100MB/s AOD 20MB/s ESD AO D TAG files/DB Flow of Configuration Data More 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 transfer Tier 0 Prompt Reconstruction Express Reconstruction, calibration Tier 1 Reprocessin g Tier 2 MC production Conditions Database Trigger Menus into Conditions DB Conditions Database TriggerDB DbProxy LVL2 Result EF Result RODs Front-end LVL2 Subfarm Input EF Event Builder LVL1/ CTP Subfarm Output EF Trigger Result Trigger 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 System12 Trigger Information for trigger studies and physics analysis Configuration Data in Offline Analysis TriggerDB All 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 Decoded trigger menu Persistence ESD Event Summary Data AOD Analysis Object Data Decoded Trigger Menu Configures for Data taking Trigger Information (transient) Transient

Thursday, September 6 The ATLAS Trigger Configuration System13 Analysis and Trigger Studies Common: check if event passed a desired trigger Trigger efficiency, luminosity calculations (on TAG DB) Navigate to trigger object that caused trigger-accept Z  ee trigger + single electron trigger to study electron trigger efficiency Rerunning the trigger without reconstruction of trigger objects Run 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 System14 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 Mode Change prescale factors or trigger menu to react on changing detector or beam conditions User Mode Browse: trigger menus, detailed information like algorithm parameters Expert mode Upload new and manipulate existing configurations Intuitive JAVA based GUI to browse and manipulate trigger configurations Search results Edit pane (e.g. for chains)

Thursday, September 6 The ATLAS Trigger Configuration System15 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 System16 Commissioning HLT Configuration Large Scale Tests in December 2006 Simple trigger setup, large computing farm: 600 dual core processors TriggerDB 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 menus Exercising 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 System17 Trigger Configuration for Simulation Production Advantages Consistency 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 release Can 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 System18 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