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 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

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

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

Status 3 http://cern.ch/alice-daq/DA-framework/ 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/

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

Parameters from MCS available in DCS archive + B field data Name Description Type Solenoid Emergency Shutdown Fast Dump or Slow Dump Boolean Steady State Current Setting = Current Read Ramping Ramping up and down Polarity Positive = TRUE, Negative = FALSE Current [A] Analog Set Current Temperature IN Temperature of water in [C] Temperature OUT Temperature of water out [C] Dipole

! Facts Calibration data size OCDB query during reconstruction 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 !

To do list Detectors SHUTTLE File Exchange Server 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

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