Commissioning of the ALICE HLT, TPC and PHOS systems Kalliopi Kanaki University of Bergen

Norwegian participation in: High Level Trigger (HLT) Time Projection Chamber (TPC) PHOton Spectrometer (PHOS) Online calibration framework Front-End Electronics (FEE) for TPC/PHOS ALICE GRID computing

Aims of HLT Lossless data compression to match data acquisition and mass storage bandwidth Online event reconstruction → fast pattern recognition (online tracking) Physics triggers (e.g. open charm, J/ψ, jets, dielectrons) → event characterization Rates of 1 kHz for p+p and 200 Hz for Pb+Pb (central) 3

HLT Processing Data Flow DAQ: DAta Acquisition ECS: Experiment Control System DCS: Detector Control System

The TPC Detector Ongoing Norwegian contribution: 845 < r < 2466 mm Drift length 2×2500 mm 557568 readout pads Ongoing Norwegian contribution: Online cluster finding & tracking Online krypton gas gain calibration

Online HLT Tracking – Dataflow Cluster Finder Track Finder/Fitter Global Merging 36 Sectors further analysis…

Online Cluster Finder ADC sequences above threshold as input Simple sequence matching between neighbouring pads Centroids calculated as weighted mean of ADC values Assigned 3D coordinates Deconvolution scheme: split clusters at local minima of charge distributions along time and pad direction

Online Tracking Algorithm real space 3D space points as input Conformal mapping conformal space “Follow-your-nose”: build tracks from outer to inner TPC-radius

HLT Cluster Status Full connectivity / all detectors included Additional CPU power is expected

Benchmarks on HLT cluster - preparation for p+p runs Setup for 1 sector 6 ClusterFinders running in parallel on 6 CPUs 1 Tracker running on 1 CPU Results (with current configuration): ClusterFinder: 240 Hz Tracker: ~200 Hz (design value 1 kHz) Significant improvement expected with additional CPU power

Event Display for Primaries HMPID TPC PHOS offline HLT

HLT and Offline Efficiency for Primary Particles Overall Efficiency: HLT: 95% Offline: 94% HLT and offline analysis deliver comparable results Running HLT code in AliRoot framework → comparison with full generator events (Pythia) 12

Krypton Gain Calibration Kr decay products (e-,γ) deposit known energy Dedicated cluster finder because of larger clusters Energy calibration possible 9.4 keV 12.6 keV 29 keV 41.6 keV 19.6 keV

The PHOS Detector Information about the initial phase of the collision High granularity electromagnetic calorimeter split in 5 modules 17920 detection channels of lead-tungstate crystals (PbWO4) Optimized for measurements of γ (0.5 - 10 GeV/c), π0 (1 - 10 GeV/c) and η mesons (2 - 10 GeV/c)

PHOS - HLT Operation Principle 2 channels per crystal PHOS extract amplitude & timing information HLT for PHOS Online monitoring & calibration Shower & μ reconstruction DAQ Offline condition database MIPS deposit ~210 MeV in one crystal length → peak in the energy distribution

Online Calibration Framework Motivation: Several ALICE systems (DCS, DAQ, ECS, Offline) provide data, settings and tools required for producing and monitoring calibration data System interfaces for data exchange Provide similar environment to online Analysis Software / Detector Algorithms (DA) as in offline 17

HLT cluster ECS DCS DCS values Control DAQ Processed events DCS-portal (Experiment Control System) DCS (Detector Control System) DCS values Control DAQ (Data Acquisition) Processed events DCS-portal (Pendolino, FED) ECS- proxy Calculated values Trigger decisions DDL Online event monitoring AliEve (ALICE Event Monitor) HLT cluster HOMER FEP Event data OFFLINE FEE (Front-End- Electronics) Calibration data OCDB (Offline Conditions DB) OFFLINE-portal (Shuttle, Taxi) DAQ (Data Acquisition) New calculated calibration data Shuttle FEP = Front-End-Processor, DDL = Direct Data Link HOMER = HLT Online Monitoring Environment including ROOT

Summary & Outlook... TPC/1st PHOS module operational, cosmics run PHOS module calibrated with cosmics HLT for TPC and PHOS operational for first physics runs Similar efficiencies for primaries in offline and HLT Kr gas gain calibration for TPC implemented Most online calibration interfaces implemented and tested & Outlook... TPC/PHOS are being connected/commissioned Integrated test with lasers/cosmics in December Kr calibration test in February On the way to p+p…

Backup slides

Calibration Input & Output DCS Input  Output  SCADA AliEn (Grid) HLT - cluster Front End Devise -portal Taxi Taxi-portal FED API OCDB (Offline) Calibration settings OFFLINE DA OCDB Shuttle- portal Meta Data DB Shuttle Pendolino Calibration& Conditions Pendolino- portal FXS Amanda Data preparation Monitoring (AliEve) Data Subscriber portal DCS Archive DB current DCS conditions Homer 21

PHOS Commissioning PHOS cosmics run Calibration of crystal gains using cosmic muons MIPS deposit ~210 MeV in one crystal length → peak in the energy distribution Equalization of electronic gains Absolute energy calibration HLT for PHOS Data compression Data integrity checks Event display Histogram plotting 22 22