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Calibrating ALICE

Calibrating ALICE. Basics. All ALICE detectors need calibration Calibration parameters must be available on the flight for the first pass reconstruction following shortly data taking Calibration parameters can be fine tuned offline for the second pass reconstruction

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Calibrating ALICE

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  1. Calibrating ALICE

  2. Basics • All ALICE detectors need calibration • Calibration parameters must be available on the flight for the first pass reconstruction following shortly data taking • Calibration parameters can be fine tuned offline for the second pass reconstruction • Calibration parameters, which are dependent on statistics can be improved continuously • Responsibilities • The calibration strategy and algorithms are under responsibility of the detector experts • The calibration framework is the responsibility of DAQ, HLT and Offline groups • The coordination is the responsibility of the Commissioning Task Force

  3. Status 1 • All detectors have a well defined calibration strategy; they know how : • to convert raw data into calibrated data • to reconstruct with dead/noisy channels • to calculate the calibration parameters and collect dead/nosy channels • the size of the raw and final calibration data sets • the running condition to acquire calibration data • to store and access offline the calibration parameters • Most of the detectors have implemented 1. and 6. in the offline framework • It is presently used in the simulation and reconstruction of the PDC

  4. Status 2 • The Offline framework is operational (see FCA at Bologna): • It provides access to calibration parameters: OCDB • It provides the mechanism to collect the calibration parameters and to store them into OCDB (Shuttle) • Attention: OCDB contains pointer to the data (root files), the files are stored on the GRID

  5. Status 3 • The DAQ Online framework is ready, it provides: • the rules to process calibration data: LDC, GDC, monitoring cluster • tools to store result files from 1. in the DAQ File Exchange Server • tools to read/write detector-specific config files in the DAQ db • example code for both use-cases (LDC/GDC files &monitoring), including a small "support" library to package the algorithm (rpm) • documentation • Guinea pigs: SPD and TOF • Reference document at http://cern.ch/alice-daq/DA-framework/

  6. Status 4 • User requirements & progress monitoring have been collected from all detectors : • Calibration and reference data format and size in OCDB • Source of data: physics run, calibration run, DAQ, HLT, DCS monitored parameters • Running conditions: update frequency, run/trigger type, statistics • Online -> Offline • Accessibility, implementation of algorithms http://aliceinfo.cern.ch/static/Documents/Computing_Board/R.htm

  7. Parameters from MCS available in DCS archive + B field data

  8. Facts • Calibration data size • Per data set (update every run, 400 runs/year) for all ALICE • In OCDB (final calibration data): > 228 GB – very high • Raw calibration data > 6610 GB • Anticipated in the Computing Model: 100 GB/year • We might need to review the UR • OCDB query during reconstruction • 1 Hz catalogue access frequency (the catalogue is centrally located at CERN) • The calibration files will are replicated at several locations around the world !

  9. To do list • Detectors • Complete and revise the requirement document • Data size in FES, OCDB and reference • Implement the online algorithms (not yet started, except SPD and T0-TOF combined time zero calibration) • SHUTTLE • Framework (Offline) done • Pre-processor: detector calibration algorithms and ROOTification (detectors) not started • File Exchange Server • File system definition (DAQ done, DCS & HLT started) • Online framework (DAQ in progress, DCS & HLT started) • Parameters evaluation (detectors) not started • HLT access to condition parameters • Discussion started

  10. Milestones • Monitor progress of detector readiness in Summer 2007 • Raw data format (Cvetan) • Calibration issues (Alberto) • Alignment issues (Raffaele) http://pcaliweb02.cern.ch/Collaboration/Boards/Computing/Planning/Milestones.html

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