Implementation of DHLT Monitoring Tool for ALICE Seforo Mohlalisi – UCT Supervisor : Z. Buthelezi (iThemba Labs)‏ Co-Supervisors : Z.Z. Vilakazi (iThemba Labs)‏ R. Fearick (UCT)‏

Outline Introduction to ALICE Muon Spectrometer Dimuon High Level Trigger (dHLT)‏ Purpose of dHLT monitoring How to implement monitoring Other work

Introduction to ALICE Its assemble of detectors Study strongly matter at extreme energy densities Production of hadrons, electrons, muons, photons SA works on muon arm

ALICE

Muon Spectrometer Detects muon from decays of J/Ψ and γ Lots data of produced and bottle neck DAQ High Level Trigger (HLT) – high selectivity Triggering Select region of interest Data Compression HLT is made up of cluster of computers placed between FEE and DAQ Dimuon HLT specifically for dimuon arm

HLT Architecture The detectors receive the trigger signals and the associated information from the Central Trigger Processor (CTP), through a dedicated Local Trigger Unit (LTU)‏ interfaced to a Timing, Trigger and Control (TTC) system. The readout electronics of all the detectors is interfaced to the ALICE standard Detector Data Links (DDL). The data produced by the detectors (event fragments) are injected on the DDLs. At the receiving side of the DDLs there are PCI boards, called DAQ Read-Out Receiver Cards (D-RORC). The D-RORCs are hosted by PCs, the Local Data Concentrators (LDCs). Each LDC can handle one or more D-RORCs. The D-RORCs perform concurrent and autonomous DMA transfers into the PCs memory, with minimal software supervision. In the LDCs, the event fragments originated by the various D-RORCs are logically assembled into sub-events. The role of the LDCs is to ship the sub-events to a farm of PCs called Global Data Collectors (GDCs), where the whole events are built (from all the sub-events pertaining to the same trigger). Besides having a DDL common to all the sub-detectors, the other major architectural feature of the ALICE data acquisition is the event builder, which is based upon an event building network. The sub-event distribution is performed by the LDCs, which decide the destination of each sub-event. This decision is taken by each LDC independently from the others (no communication between the LDCs is necessary); the synchronization is obtained using a data-driven algorithm. The algorithm is designed to fairly share the load on the GDCs.

DHLT Analyses data online to select events relevant to muons reconstructing clusters, hits, trigger records, tracks Pub/Sub framework Monitoring e.g. visualization and error handling

Detector Control System DHLT COMPONENTS Detector Control System And Conditions Database HLT Control Task Manager Tracking Chamber readout Trigger Chamber Readout Detector Calibration Data Detector Configuration data DDL stream data DDL stream data Online hit reconstruction Tracking Algorithm dHLT decision maker DDL stream data Monitoring data To DAQ To dHLT Monitoring

Monitoring Visualization of event Raw data, Hits, tracks, trigger records Plots Transverse momentum (pt) - distributions and cuts Efficiency curves (iii) Invariant mass spectra, etc Scalers : number of tracks found, number of events processed etc. Status information : connection status, error messages

Objectives Improving existing framework message queue Data channels and channel manager Extend ALIEVE (ALICE Event Visualization Environment) Displaying and handling of errors

Monitoring Structure

Other work: Auxiliary Tools Implemented dHLTdumpraw for dumping DDL data from muon spectrometer DHLT internal data block clusters, tracks etc Implemented findLibDeps.py Locates library dependencies For standalone compilation Testing muon raw data decoder

Other work: Analysis CERN summer school project – Offline Based Convert existing macro to analysis task CheckESD.C to AliAnalysisTaskCheckESD Calculate physics efficiency, PID, Resolution Core components of Analysis Task: UserCreateOutputObjects, UserExec, Terminate All tasks inherit from AliAnalysisTaskSE

Analysis Cont... Multiple data sources Multiple platforms ESD, AOD, MC Truth Multiple platforms Locally,Proof,Grid Discovered several problems Missing track in muon reconstruction Low efficiency in PHOS detector

…..END “I do not know what I may appear to the world, but to myself I seem to have been only a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.” Isaac Newton