1 HLT – a source of calibration data One of the main tasks of HLT (especially in the first years) –Monitoring of the detector performance –Analysing calibration data (real events and calibration triggers) –Calculation of a (first) set of calibration parameters –Applying calibration to online event reconstruction –Storing parameters in relevant databases Procedures are being developed in collaboration with TPC, PHOS and Dimuon detector HLT is open for calibration tasks for all participating detectors

2 TPC calibration (1) Pedestal runs –Accumulation of empty black events –Configuration of FEE with averaged pedestal values –Monitoring of pedestal quality/stability –Minimal computing needs, no storage of pedestals in database (perhaps initially in FERO DB) –This task could also be executed on LDCs Pulser runs –Accumulation of pulser events –Gain calibration and timing alignment –Map hot/dead pads

3 TPC calibration (2) Drift velocity map –Nuclear collisions –Accumulate charge per timebin –Calculate charge step at central electrode –E.g. NA49 data NA49 charge step

4 TPC calibration (3) Laser runs –Online reconstruction of laser tracks –Drift velocity map Electron attachment / gas contamination –Online reconstruction of particle tracks / laser tracks –Cluster charge loss per drift length

5 TPC calibration (4) Space charge effects –Online reconstruction of tracks –Histogram of track impact parameters –E.g. STAR TPC – fluctuations on second timescale

6 TPC calibration (5) –Histogram of track residuals –E.g. STAR TPC – grid leak distortions »Ion leakage at gating grid gap

7 PHOS online processing Pulse shape analysis –Amplitude -> Energy –Timing -> TOF –reduces data volume by a factor of ~25 Gamma-2 fit Peak Method : Offline time reference at peak ( y’ =0 ) Slope Method:Offline time reference at max. slope ( y”=0 ) (both reference points are amplitude independent)

8 PHOS calibration (1) Pedestal runs –Accumulation of empty black events –Configuration of FEE with averaged pedestal values –Monitoring of pedestal quality/stability LED runs –Accumulation of pulser events –Gain calibration and timing alignment –Map hot/dead channels

9 PHOS calibration (2) Gain/energy calibration –Using particle data –Online pulse shape analysis –Timing alignment (using fastest particles) –Online reconstruction and accumulating of showers –Relative gain calibration by equalizing channels –Absolute energy calibration by monitoring pi0-peak