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HMPID weekly meeting

Update on p-Pb spectra

G. Volpe

31/10/2013

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Spectra in p-Pb collisionsp Pb

• proton beam energy = 4 TeV;

• proton energy in lead nuclei = 4x82/208 ≈ 1.58 TeV;

• Center of mass energy per nucleon pair = 2(4x1.58)0.5 ≈ 5.02 TeV;

• The center of mass moves in the lab. frame with rapidity Y = - 0.465.

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Spectra in p-Pb collisionsTotal statistic• p-Pb 5.02 TeV, LHC13b (EDSs pass3): ≈ 20 millions MB events

• p-Pb 5.02 TeV, LHC13c (ESDs pass2): ≈ 70 millions MB events

• Centrality (multiplicity) selected using the amplitude of the signal of V0A detector;

• Spectra evaluated in the rapidity range 0 < YCMS < 0.5;

• YLAB = YCMS – 0.465, 0 < YCMS < 0.5 corresponds to -0.465 < YLAB < 0.035

• For each mass hypothesis a cut on YLAB has been applied and the corresponding raw yields has been evaluated.

• The main corrections have been estimated from Monte Carlo:• MC productions: LHC13b2_efix_p1, LHC13b2_efix_p2

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Spectra in p-Pb collisions: pions

Corrected spectra

PRELIMINARY

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Spectra in p-Pb collisions: kaons

Corrected spectra

PRELIMINARY

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Spectra in p-Pb collisions: protons

Corrected spectra

PRELIMINARY

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF+rTPC): 0-5 %

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF+rTPC): 5-10 %

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF+rTPC): 10-20 %

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF+rTPC): 20-40 %

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF+rTPC): 40-60 %

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF+rTPC): 60-80 %

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF+rTPC): 80-100 %

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF)

Pions

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF): kaon

K+

Kaons

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Comparison HMPID spectra with combined spectra (ITS+TPC+TOF): proton

p

Protons

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Spectra in p-Pb collisions: pions & kaons < 4 GeV/c

Very preliminaryPositive

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Spectra in p-Pb collisions: pions & kaons < 4 GeV/c

Very preliminaryNegative

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Conclusions

• p-Pb corrected spectra have been evaluated in all events classes (V0A 0-100%).

• Main corrections have been applied (tracking eff., PID eff., distance cut).

• Pions and kaons spectra pushed up to 4 GeV/c (very preliminary)!!

• To do: • Further increase Monte Carlo statistic for tracking and PID

efficiency evaluation?• Cross check PID efficiency from MC with that extracted from real

data (V0’s decays).• Estimate GEANT-FLUKA and feed-down correction.• Systematic uncertanties.

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Backup

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Spectra p-Pb (0-5%): Fit examples

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Spectra p-Pb (40-60%): Fit examples

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Spectra in p-Pb collisions: tracking efficiency

• Tracking efficiency convoluted with the detector acceptance in the required rapidity range;

• MC productions: LHC13b2_efix_p1, LHC13b2_efix_p1, LHC13b2_efix_p3

• The corresponding correction is obtained by fitting such distributions

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Spectra in p-Pb collisions: PID efficiency

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Spectra in p-Pb collisions: distance cut correction