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HMPID plenary meeting

G. Volpe

HMPID offline and analysis status report

CERN, 22/03/2013

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• 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:

virtual EDetPidStatus ComputeHMPIDProbability(const AliVTrack *track, Int_t nSpecies, Double_t p[]) const;virtual Float_t NumberOfSigmasHMPID(const AliVParticle *track, AliPID::EParticleType type) 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.

HMPID offline update

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HMPID module

Tin

Tout

Tin

Tin

Tout

Tout

Radiator vessel 1

Radiator vessel 2

Radiator vessel 3

Nfreon = f(Temp,Ephoton)

• 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.

x

y

Temperature gradient

HMPID offline update

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• 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.

HMPID offline update

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

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Data vs Monte Carlo

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

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).

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

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Monte Carlo vs data

protons

• 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).

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

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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 TeV LHC11c (pass1): ≈ 100 millions of events, half old tracking, half new tracking;

• pp 7 TeV LHC11d (pass1): ≈ 20 millions of events, new tracking;

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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;

• …………………………………………………?

Total statistic collected up to now

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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-Pb 5.02 TeV MB events: ≈ 100*106

Total statistic collected up to now

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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.

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Pb-Pb analysis status

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Pb-Pb analysis status

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.

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

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Pb-Pb analysis status: raw hadron ratios

Protons Kaons

Pions

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Pb-Pb analysis status: comparison with TOF

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

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Pb-Pb analysis status: corrections for protons

LHC12a17a

LHC12a17b_fix

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

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Pb-Pb analysis status: corrections for protons

ProtonsAnti-prototns

From Francesco

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.

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Pb-Pb analysis status

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

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Backup

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Negative/positive ratio

Total negative/total positive tracks in HMPID acceptance

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• Module 4 and 6• Module 0 and 2

6 5

4 3 2

1 0

Position of TPC membrane

A side C side

Analysis status: Pb-Pb at 2.76 ATeV

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