HMPID plenary meeting

1. HMPID plenary meeting HMPID offline and analysis status report G. Volpe CERN, 22/03/2013

2. 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.

3. 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.

4. 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!!

5. 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).

6. 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

7. Bayesian PID • Propagation factors to adapt priors to detectors: to be redone with more statistic

8. 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;

9. 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; • …………………………………………………?

10. 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

11. 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.

12. Pb-Pb analysis status

13. 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.

14. Pb-Pb analysis status: raw hadron ratios Kaons Protons Pions

15. Pb-Pb analysis status: comparison with TOF TOF ratio evaluated using n-sigma method. 2 sigmas cut has been applied

16. 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

17. 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.

18. Pb-Pb analysis status pbar/p ratio corrected for PID efficiency and cut distance correction factor

19. Backup

20. Negative/positive ratio Total negative/total positive tracks in HMPID acceptance

21. 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