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HMPID plenary meeting. HMPID offline and analysis status report. G . Volpe. CERN, 22 /03/2013. HMPID offline update. Correction factor for the Cherenkov angle resolution implemented and committed to the trunk.

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slide1

HMPID plenary meeting

HMPID offline and analysis status report

G. Volpe

CERN, 22/03/2013

slide2

HMPID offline update

  • Correction factor for the Cherenkov angle resolution implemented and committed to the trunk.
  • Code implementation to allow calculation of angular resolution, PID probability and n-sigma, also at analysis level based on ESDs or AODs, done:
    • Central AliRoot classes have to be modified.
      • AliPIDResponse,AliVTrack, AliAODTrack, AliAODHMPIDRings
      • Missing AOD getter implemented.
      • New methods in AliPIDResponse class:
  • virtualEDetPidStatusComputeHMPIDProbability(constAliVTrack*track, Int_tnSpecies, Double_t p[]) const;virtualFloat_tNumberOfSigmasHMPID(constAliVParticle*track, AliPID::EParticleTypetype) const
    • New classes have to be implemented:
      • STEER/STEERBase/AliHMPIDPIDResponse(re-doing calculations already done in HMPID classes)
      • STEER/STEERBase/AliHMPIDPIDParams
    • Refractive index values will be stored in the OADB.
slide3

HMPID offline update

Nfreon = f(Temp,Ephoton)

y

Tout

Radiator vessel 1

Tin

Tout

HMPID module

Temperature gradient

Radiator vessel 2

Tin

Tout

Radiator vessel 3

Tin

x

  • At reconstruction level temperature and photon energy are read from OCDB, where these information are stored online run by run.
  • No run by run temperature variation have been observed. Variation introduced only by radiator condition (circulating or stagnant)
  • TF1 objects containing refractive index values vs local y coordinate for each chamber will be stored in the OADB.
slide4

HMPID offline update

  • New code already in the trunk.

Cherenkov signal vs momentum for pions, kaons and protons selected using n-sigmas cut, calculated with the new code. The plot refer to ≈ 300000 p-p 7 TeV events.

Important: HMPID analysis should migrate on AODs, in this way will be much faster!!

slide5

Data vs Monte Carlo

  • Monte Carlo describes quite well the HMPID response function, both in pp and in PbPb data.

Number of reconstructed photo-electros vs sin2(qckov) in data and Monte Carlo

Rapidity distribution for protons in HMPID acceptance. Comparison data Monte Carlo. In data protons have been selected using track-by-track HMPID PID (real acceptance).

slide6

Monte Carlo vs data

  • s of the Monte Carlo Cherenkov angle distributions are in good agreement with the real one;
  • There is a small shift in the mean value: refractive index used in Monte Carlo is a bit different w.r.t. the real one (some weeks to finalize it).

protons

slide7

Bayesian PID

  • Propagation factors to adapt priors to detectors: to be redone with more statistic
slide8

Total statistic collected up to now

  • 2010
  • pp 7 TeV, LHC10b and LHC10c (pass3): ≈ 80* millions of MB events, new tracking;
  • pp7 TeV, LHC10d (pass2): ≈ 200 millions of events, old tracking;
  • pp 7 TeV, LHC10e (pass2): ≈ 200 millions of events, old tracking;
  • PbPb 2.76 ATeV, LHC10h (pass2): ≈ 10* millions of MB events , old tracking;
  • 2011
  • pp 2.76 TeV, LHC11a (pass3): ≈ 50* millions of MB events, new tracking;
  • pp 7 TeV, LHC11b (pass1): ≈ 50 millions of events, old tracking;
  • pp 7 TeVLHC11c (pass1): ≈ 100 millions of events, half old tracking, half new tracking;
  • pp 7 TeVLHC11d (pass1): ≈ 20 millions of events, new tracking;
slide9

Total statistic collected up to now

  • 2011
  • pp 7 TeV, LHC11e (pass1): ≈ 40 millions of events, new tracking;
  • PbPb 2.76 ATeV, LHC11h: ≈ 10* millions of central events, ≈ 10 millions of semi-central events, few millions of MB events, new tracking.
  • 2012 (MB events fraction rather small)
  • pp 8 TeV, LHC12a (pass1): ≈ 50 millions of events, new tracking;
  • pp8 TeV, LHC12b (pass1): ≈ 70 millions of events, new tracking;
  • pp8 TeV, LHC12c (cpass1): ≈ 30 millions of events, new tracking;
  • pp8 TeV, LHC12d (pass1): ≈ 30 millions of events, new tracking;
  • pp8 TeV, LHC12f (pass1): ≈ 10 millions of events, new tracking;
  • pp8 TeV, LHC12g and LHC12h (cpass1): ≈ 6 millions if events, new tracking;
  • …………………………………………………?
slide10

Total statistic collected up to now

  • 2013
  • p-Pb 5.02 TeV, LHC13b (pass2): ≈ 27 millions MB events
  • p-Pb 5.02 TeV, LHC13c (pass1): ≈ 70 millions MB events
  • Total p-p 8 TeV MB events: ≈ 20*106?
  • Total p-p 7 TeV MB events: ≈ 800*106
  • Total p-p 2.76 TeV MB events: ≈ 50*106
  • Total Pb-Pb 2.76 ATeV events: 10*106 MB, 10*106 central (0-10%), 10*106 semi central (10-50%).
  • Total p-Pb5.02 TeV MB events: ≈ 100*106
slide11

QA

  • Productions (both data and MC) regularly checked (by Marco). No reconstruction code issues discovered .
  • Hardware issue in chamber 5 in p-Pb data (LHC13b): problem with zero suppression.
  • QA plots stored in the HMPID twiki page https://twiki.cern.ch/twiki/bin/viewauth/ALICE/QA.
slide13

Pb-Pb analysis status

pbar/p ratio in Pb-Pb collisions provided by means of statistical unfolding in HMPID corrected for tracking efficiencies.

pbar/p ration in pPb collisions provided by means of statistical unfolding in TOF. Small decreasing is present, very likely due to wrong efficiencies corrections.

slide15

Pb-Pb analysis status: comparison with TOF

TOF ratio evaluated using n-sigma method. 2 sigmas cut has been applied

slide16

Pb-Pb analysis status: corrections for protons

Tracking efficiency convoluted with HMPID acceptance for two different anchor MC productions. No difference between protons and anti-protons, also a low momenta?!

LHC12a17a

LHC12a17b_fix

slide17

Pb-Pb analysis status: corrections for protons

From Francesco

Protons

Anti-prototns

PID efficiency for protons and anti-protons, extracted by means of V0s selection. Difference between the two charge is present.

Correction factor due to distance track-MIP cut, for negative and positive tracks.

slide18

Pb-Pb analysis status

pbar/p ratio corrected for PID efficiency and cut distance correction factor

slide20

Negative/positive ratio

Total negative/total positive tracks in HMPID acceptance

slide21

Analysis status: Pb-Pb at 2.76 ATeV

6

5

  • Module 4 and 6
  • Module 0 and 2

4

3

2

1

0

A side

C side

Position of TPC membrane