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A Very High Momentum Particle Identification Detector for the ALICE experiment at the LHC.
Dorado del mar Puerto Rico, April 8, 2012
Edmundo GarcíaChicago State University
for the VHMPID Group
28th Winter Workshop on Nuclear Dynamics
Cherenkov Radiation2
symmetric dipole distribution incoherent destructive interference
symmetric dipole distribution coherent Cherenkov radiation
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”
ALICE PID
separation @ 2s
VHMPID
separation @ 3s
VHMPID
Existing gap between low and high pT ALICE for detailed (3 s) hadron PID
9
ALICE rdE/dx and VHMPID
rdE/dx• Statistical, reaching high-pT
• Clean π sample• Protons are difficult• No kaon PID
VHMPID• Track-by-track• Difficult at low pT
• 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 (20o each)
• 30% central barrel acceptance• C4F10 (C4F8O) at gas pressure
3 atm, 40o 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
• Transition Radiation Detector trigger
• 6 tracking layers 400 – 600 resolution
• Readout 200 Hz 5% dead time• Trigger based on matching at
least 4 track segments, track threshold 5 GeV/c pT
15
Triggering HPTD16
• Close Cathod Chambers*
• Provides L0 trigger for pp• Provides of L1 trigger PbPb• MIP detection *G. Hamar, G. Kiss, D. Varga: Nucl.Instrum.Meth. A648 163-167 (2011)
Performance Simulations17
0 . 0 0 0 0
0 . 0 7 1 6
0 . 1 4 3 1
0 . 2 1 4 7
0 . 2 8 6 2
0 . 3 5 7 8
0 . 4 2 9 4
0 . 5 0 0 9
0 . 5 7 2 5
0 . 6 4 4 1
0 . 7 1 5 6
D e t e c t o r I m a g e : I n c o h e r e n t I r r a d i a n c e
3 / 7 / 2 0 1 2D e t e c t o r 1 , N S C G S u r f a c e 1 : S i z e 2 0 0 0 . 0 0 0 W X 2 0 0 0 . 0 0 0 H M i l l i m e t e r s , P i x e l s 2 5 0 W X 5 0 0 H , T o t a l H i t s = 1 2 0 0 0 0 0P e a k I r r a d i a n c e : 7 . 1 5 6 2 E - 0 0 1 W a t t s / c m ^ 2T o t a l P o w e r : 1 . 2 0 0 0 E + 0 0 1 W a t t s
Mirror misalignment simulation
Center 1
Center 2 10 GeV/c pions and
kaons
Chromatic dispersionlimited detector resolution
Reconstructed Cherenkov angle in PbPb background
High-pT physics in proton-proton collisions
• Preset FF set are extracted from global data fits from and RHIC spectra
• NLO calculations uncertainty is large in the comparison to experimental data
• Improved PID in ALICE could significantly contribute to improve the constraints on the FFs with through high-pT identified particle spectra
19
F
S. Albino, A Kniehl, G. Kramer Nucl.Phys.B803, 42-104,2008
S. Albino, A. Kniehl, G. Kramer Phys. Rev. Lett 104, 242001, 2010CDF et al Phys. Rev. D. 79, 112005 , 2009
S. Albino, A Kniehl, G. Kramer Nucl.Phys. B803, 42-104,2008
Track - by - Track PID and Jets application20
• 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:0807.3123v1 [hep-ex]
Study of Hadronization and Jet Quenching in Pb-Pb21
• Need more differential probes to understand hadronization in medium and medium properties.
• Particle identification at high pT , should be the basis for most potentially new measurements
Sapeta, Wiedemann Eur.Phys.J.C55:293-302,2008
P. Levai, D. Berenyi, A. Pasztor, and V.V. Skokov, Jour. Phys. G38 (2011)
High-momentum resonance production
• Reconstructed - meson peak in invariant mass distribution for k+k- pairs in min. bias PbPb collisions at 5.5 ATeV
• VHMPID acceptance based on 5 Million central HIJING events
• S/B 10 : 1
22
Present vs. ideal TPC performance
Kaon contamination in pp slightly higher at similar pT compared to PbPb
Resolution in pp (5.4%) slightly better (6.1% in PbPb)
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