A Very High Momentum Particle Identification Detector for the ALICE experiment at the LHC. Dorado del mar Puerto Rico, April 8, 2012 Edmundo García Chicago State University for the VHMPID Group 28 th Winter Workshop on Nuclear Dynamics

Cherenkov Radiation 2 The 1958 Physics Nobel Prize was awarded jointly to P. A. Cherenkov, I. M. Frank and I. Yevgenyevich “for discovery and interpretation of Cherenkov effect”

From the Physics to the Detector 3 First used by E605 Fermilab Helium Radiator CaF 2 window

Recent Cerenkov Detectors 4 COMPASS LHCb ALICE HMPID

High Momentum Particle Identification Detector 5 MIP Cherenkov Ring

Outline Introduction The Detector Technical Notes Physics Possibilities Final Notes 6 HMPID

A Large Hadron Collider Experiment 7 EMCAL HMPID TOF TRD PMD TPC PHOS ITS MUON

Selected Detector PID in ALICE

ALICE PID 2  VHMPID 3  VHMPID Existing gap between low and high p T ALICE for detailed (3  ) hadron PID 9

Very High Momentum Particle Identification Detector 10 3  PID of π, K, p on a track-by-track basis

ALICE rdE/dx and VHMPID rdE/dx Statistical, reaching high-p T Clean π sample Protons are difficult No kaon PID VHMPID Track-by-track Difficult at low p T Limited acceptance (maximum 30% of central barrel)

Estimated improvements in Particle Production Error bars statistical plus systematic Lager yield of protons 12 Pytha Medium modification prediction by Wiedemann et al

Flow Jet Fragmentation 13 TPC based on analysis of 2010 data Improvement based on VHMPID stat & syst. error Ratio of fragmentation functions Errors depend on PID systematics, statistics, and jet energy determination

ALICE Integration VHMPID + (DCaL) or PHOS system in 5 sector (20 o each) 30% central barrel acceptance C 4 F 10 (C 4 F 8 O) at gas pressure 3 atm, 40 o C Radiator length 50 cm keeping basic performance 14 tracking layer 3 cm photo detector 9 cm radiator 50 cm mirror and insulation 9 cm tracking layer 3 cm

Triggering TRD 15

Triggering HPTD 16 Close Cathod Chambers * Provides L0 trigger for pp Provides of L1 trigger PbPb MIP detection *G. Hamar, G. Kiss, D. Varga: Nucl.Instrum.Meth. A (2011)

Performance Simulations 17 Mirror misalignment simulation Center 1 Center 2 10 GeV/c pions and kaons Chromatic dispersion limited detector resolution Reconstructed Cherenkov angle in PbPb background

VHMPID prototype 18

High-p T physics in proton-proton collisions 19 S. Albino, A Kniehl, G. Kramer Nucl.Phys.B803, ,2008 S. Albino, A. Kniehl, G. Kramer Phys. Rev. Lett 104, , 2010 S. Albino, A Kniehl, G. Kramer Nucl.Phys. B803, ,2008

Track - by - Track PID and Jets application 20 Investigate the production mechanism of heavy prompt quarkonia by studying the kinematics of jet associated particles. Characterize of the jets accompanying the J/  production in p-p collisions such as the scalar sum of transverse momentum, the fragmentation function, the cone radius, or jet composition. Compare jet characteristics in p-p and A-A collisions A.C. Kraan, arXiv: v1 [hep-ex]

Study of Hadronization and Jet Quenching in Pb-Pb 21 Need more differential probes to understand hadronization in medium and medium properties. Particle identification at high p T, should be the basis for most potentially new measurements Sapeta, Wiedemann Eur.Phys.J.C55: ,2008 P. Levai, D. Berenyi, A. Pasztor, and V.V. Skokov, Jour. Phys. G38 (2011)

High-momentum resonance production 22

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Backup Transparencies 24

The ‘golden cuts’ on rdE/dx distributions for TPC 25

Present vs. ideal TPC performance Kaon contamination in pp slightly higher at similar p T compared to PbPb Resolution in pp (5.4%) slightly better (6.1% in PbPb)

Photoelectrons Charged particle at saturation in 50 cm of C 4 F 10 at 3 atm 27

C 4 F 10 dependence vs resolution 50 cm radiator