Update on p- Pb and Pb-Pb spectra

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Update on p-Pb and Pb-Pb spectra

HMPID weekly meeting

CERN, 26/09/2013

G. Volpe

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p-Pb

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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: tracking efficiency

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

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Spectra in p-Pb collisions: PID efficiency

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Spectra in p-Pb collisions: distance cut correction

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Spectra in p-Pb collisions: minimum bias

Corrected spectra

PRELIMINARY

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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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Pb-Pb

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Spectra in Pb-Pb collisions: tracking efficiency

Tracking efficiency convoluted with the detector acceptance in the required rapidity range(MC prod. : LHC12a17a_fix)

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Spectra in Pb-Pb collisions: PID efficiency (0-5 % centr.)

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Spectra in Pb-Pb collisions: PID efficiency (5-10 % centr.)

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Spectra in Pb-Pb collisions: PID efficiency

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Spectra in Pb-Pb collisions: distance cut correction

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Spectra in Pb-Pb collisions: pions (0-50 % centr.)

Corrected spectra

PRELIMINARY

Centrality bins:0 – 5 %5 – 10 %10 – 20 %20 – 30 %30 – 40 %40 – 50 %

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Spectra in Pb-Pb collisions: kaons (0-50 % centr.)

Corrected spectra

PRELIMINARY

Centrality bins:0 – 5 %5 – 10 %10 – 20 %20 – 30 %30 – 40 %40 – 50 %

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Spectra in Pb-Pb collisions: kaons (0-50 % centr.)

Corrected spectra

PRELIMINARY

Centrality bins:0 – 5 %5 – 10 %10 – 20 %20 – 30 %30 – 40 %40 – 50 %

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Ratios

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Hadron ratios in p-Pb data: anti-part/part

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Hadron ratios in p-Pb data: K/p, p/p

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Hadron ratios in Pb-Pb data: anti-part/part

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Hadron ratios in Pb-Pb data: K/p, p/p

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Conclusions

• Pb-Pb corrected spectra have been evaluated in central and semi-central collisions (0-50%).

• 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).

• To do: • Further increase Monte Carlo statistic for PID efficiency

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

data (V0’s decays).• Estimate feed-down correction.

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Backup

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Spctra in Pb-Pb collisions: fit exapmples

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Spectra in Pb-Pb collisions: pions raw yields

Centrality bins:0 – 5 %5 – 10 %10 – 20 %20 – 30 %30 – 40 %40 – 50 %

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Spectra in Pb-Pb: kaons raw yields

Centrality bins:0 – 5 %5 – 10 %10 – 20 %20 – 30 %30 – 40 %40 – 50 %

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Spectra in Pb-Pb collsions: protons raw yields

Centrality bins:0 – 5 %5 – 10 %10 – 20 %20 – 30 %30 – 40 %40 – 50 %

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Spectra in p-Pb collisions: p/p ratio

HMPIDITS+TPC+TOF