Jacek Tomasz Otwinowski 04.26.2011

• Seem to be that the only way to check pT (scale, resolution) for combined tracking (ITS+ITS) are K0s and lambda peaks.
• For the high-pT systematic errors we make the ratio of pT distributions for:
  • TPC A-side (q+) / all
  • TPC A-side (q-) / all
  • TPC C-side (q+) / all
  • TPC C-side (q-) / all
  • Differences in the this ratios point to systematic errors in the track reconstruction.
• For EMCAL you can check (ITS+TPC) + EMCAL matching residuals (mean, sigma) for q- and q+ vs pT.

2. Cosmic tracks

• We expect a negligible contribution from cosmic tracks when ITS is included in the track reconstruction (narrow acq. window).
• For reference, have a look at TPC/AliTPCcalibCosmic.:FindCosmicPairs(const AliESDEvent * event). No need to use AliESDfriend track information which is in this function.

3. Minimum pT cut on global tracks

• Use MC for efficiency studies to set the proper threshold.

4. TPC only track

• TPC only track you can use for your analysis but if you focus on low-pT tracks (<10 GeV/c) where pT resolution is still good < 7%. If you go to high-pT (>10 GeV/c) you need to use combine tracking (ITS + TPC) asking for the first SPD layer to have longer track in B-filed or use TPC+event vertex point (ALICE jets people using it, no holes in "phi" acceptance due to ITS and the pT resolution as combine tracking).

5. Improvement in pass2

• Concerning Pb-Pb pass2, we do expect a small improvement in the pT-resolution (new space-point calibration, alignment vs time calibration).
• Concerning pp at 2.76 TeV we do not expect improvement in pT resolution.

-- RongrongMa - 24-Nov-2011