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Particle identification. RHIC, LHC (ALICE) (status and future)

Particle identification. RHIC, LHC (ALICE) (status and future). N.Smirnov. Physics Department, Yale University. JLab, Detector workshop, June 4-5, 2010. STAR Detector. B = 0.5 T. 2 m. 2 m. ALICE Detector. HMPID. EMCAL. TRD. ITS. TPC. TOF. PHOS. 3. STAR; dE/dx at low pT.

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Particle identification. RHIC, LHC (ALICE) (status and future)

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  1. Particle identification.RHIC, LHC (ALICE)(status and future) N.Smirnov. Physics Department, Yale University JLab, Detector workshop, June 4-5, 2010.

  2. STAR Detector B = 0.5 T 2 m 2 m

  3. ALICE Detector HMPID EMCAL TRD ITS TPC TOF PHOS 3

  4. STAR; dE/dx at low pT On-line TPC track reconstruction Time Projection Chamber: STAR: 45 padrow, 2 meters (radius), s(dE/dx)8.2%, ALICE: 160 padrow, 2.5 meter (radius), σ(dE/dx)  (5.8-7.)% -1<<1

  5. TPC PiD, Topology and Mass Reconstruction (STAR) • Topology analysis (V0s,Cascades, -conversion, “kink”-events…) • limitation in low pT, and stat.

  6. Gas detector (TPC) simulation.Tracking and dE/dX performance -- FVP approach *) -- Monte-Carlo program was prepared to simulate number of interactions (and position along the particle track), and a transfer energy in each interaction as a function of a gas mixture parameters and particle momentum (βγ). -- GEANT3, detail and careful detector response simulation *) All details can be found: -- H. Bichsel, NIM A562 (2006) 154 -- http://faculty.washington.edu/hbichsel/

  7. STAR TPC; experiment – simulation comparison (dE/dX and PID analysis – in “Nσ“ for {log(q / <q>)/σ+9}.) Simulation: Try to be ACAP with number of Hits / track; and use the same Truncated approach. Data from O. Barannikova, Proc. 21st Winter Workshop on Nuclear Dynamics (2005). π π p p K K Nσ

  8. STAR TPC; experiment – simulation comparison • Pt, GeV/c (Nσ, K - Nσ, π) (Nσ, p - Nσ, π) { experiment *) / simulation } • 3.125 -1.68 / -1.68 -2.03 / -2.08 • 4.25 -1.67 / -1.72 -2.35 / -2.45 • 6.25 -1.61 / -1.69 -2.51 / -2.59 • 11.0 -1.44 / -1.44 -2.27 / -2.35 • Conclusion:Simulation approach reproduced experimental data ( STAR, P10). *) Yichun Xu, … arXiv:0807.4303v1, 27 July 2008

  9. Simulation result for ALICE TPC;the same approach, but 90% cluster finding efficiency and “optimal” truncated procedure dE/dX as a function of momentum dE/dX as a function of βγ π K p P, GeV/c βγ

  10. ALICE TPC; PiD performance (on a “track level”) Particle momentum – 4. GeV/c Proton identification: Efficiency – “purity” π p K Nσ Cut parameter For 70% efficiency – 70% “purity”

  11. ALICE TPC; PiD performance (on a “track level”) Particle momentum – 10. GeV/c Proton identification: Efficiency – “purity” π p K Nσ Cut parameter For 70% efficiency – 70% “purity”

  12. ALICE TPC; PiD performance (on a “track level”) Particle momentum – 15. GeV/c Proton identification: Efficiency – “purity” π p K Nσ Cut parameter For 70% efficiency – 70% “purity”

  13. Preliminary conclusion (personal opinion) • ALICE TPC PiD performance is not good enough to get high Pt (>10 GeV/c ) Proton identification on a “track level”. • Most probable – simulation results are too optimistic • In “real” experiment: -- cluster finding and track reconstruction is not easy busyness. It is never can be done perfect because of track overlaps, background, distortions. -- gas amplification and noise have “additional” variations (along wire, wire-to-wire, P/T, …) and should be careful calibrated and under control. • My forecast is “60 – 60”. But the first run will demonstrate.

  14. dE/dx kaons protons deuterons pions electrons STAR Detectors run II Au+Au @ 200 GeV STAR Time Projection Chamber |h|<1.5 and Df = 360o CERN-STAR Ring Imaging Čerenkov Detector dE/dx PID range: [s (dE/dx) = .08] p  ~ 0.7 GeV/c for K/  ~ 1.0 GeV/c for p/x Prototype (ALICE, small acceptance) r ~ 235cm, s~1.1m2 |h|<0.3 and Df = 20o

  15. RICH Identification 3) Ring reconstruction • Charged particle through radiator • MIP and photons detection 4) Response simulation STAR preliminary Liquid C6F14 RICH PID range: 1 ~3 GeV/c for Mesons 1.5 ~4.5 GeV/c for Baryons Cluster charge, ADC counts, experimental data

  16. pions kaons protons Cherenkov distribution and Fitting: integrated method Cherenkov angle distribution in momentum bins • 3 Gaussians fit: • a8 (= 9-1 constraint) parameters. • constraint: integral = entries. • fixing parameters with simulation a Separate species for each momentum slice:

  17. Identified particle pT spectra 9 such detectors are working in ALICE

  18. Multigap Resistive Plate Chamber MRPC Technology developed at CERN Read out pad size： 3.15cm×6.3cm Gap: 6×0.22mm 95% C2H2F4 5% Iso-butane 3800 modules, 23,000 readout chan. to cover TPC barrel Multi-gap Resistive Plate Chamber TOFr: 1 tray (~1/200), s(t)=85ps

  19. ToF + dE/dX: “e / hadron PID” Hadron identification: STAR Collaboration, nucl-ex/0309012 nucl-ex/0407006 electrons Electron identification: TOFr |1/ß-1| < 0.03 TPC dE/dx electrons!!!

  20. ALICE experiment p/K TPC + ITS (dE/dx) K/p e /p p/K TOF K/p p/K HMPID (RICH) K/p 0 1 2 3 4 5 p (GeV/c) TRD e /p 1 10 100 p (GeV/c) • ALICE has a unique capability, among the LHC experiments, of charged particle identification, due to the exploiting of different types of detectors: • ITS + TPC : low pT identification (up to p = 600 MeV/c). • TOF : covers intermediate pT region. • TRD : electrons identification. • HMPID : high pT region (1÷5 GeV/c). with TOF data High-pT Physics at LHC, 17 March 2008 G. Volpe

  21. Definition of “high Pt” • Experience from RD26; HMPID R&D, construction and utilization in STAR and ALICE • Experience to work with micro-pattern gas detectors • RICH R&D results from BRAHMS, LHCb and COMPAS Experiment Radiator Gas and Length UV detector Pad size BRAHMS C4F10 (+) 150 cm Ph. Tubes 1.1x1.1 cm2 COMPAS C4F10 300 cm MWPCH+CsI 0.8x0.8 cm2 LHCb (RICH 1) C4F10 + AG 85 cm HPDs .25 x .25 cm2 (HERMES) • Reliable Detector response simulation • Gas quality and Index of refraction controls

  22. ALICE VHMPID design constraints • Charged hadrons (p, K, p) identification in 10 - 30 GeV/c • Focusing RICH with gaseous radiator • High Pt trigger • Limited available space in ALICE • Filling factor (acceptance), radiator length • Limited time for R&D and (possibly) detector construction • HMPID heritage and know-how: CsI, MWPC, FEE,… 07/05/2010 A. Di Mauro - RICH2010, Cassis 25

  23. Radiator gas CF4 (n ≈ 1.0005, γth ≈ 31.6) has the drawback to produce scintillation photons (Nph ≈ 300/MeV), that increase the background. C4F10 (n ≈ 1.0015, γth ≈ 18.9) C5F12 (n ≈ 1.002, γth ≈ 15.84) this gas has been used in the DELPHI RICH detector

  24. Detector principle scheme Focusing RICH, C4F10 gas radiator L~ 80 cm Photon detector a la HMPID, baseline option: MWPC with CsI pad (8x8 mm) segmented photocathode; alternative: CsI-TGEM or GEM Spherical (or parabolic) mirror, composite substrate, Al/MgF2 coating FEE based on HMPID Gassiplex chip, analogue readout for localization via centroid measurement CaF2 07/05/2010 A. Di Mauro – RICH2010, Cassis 27

  25. Integration in ALICE 11 12 11 12 TPC TRD Free slot for prototype ~ ½ supermodule • 7% acceptance wrt TPC • 12% wrt TPC in |η | < 0.5 (jet fully contained) 07/05/2010 A. Di Mauro – RICH2010, Cassis 28

  26. Expected performance The detector consists of 9 modules of 1.4 m2 corresponding to an acceptance of ~ 10% • PID performance from Cherenkov angle resolution studied in ALIROOT overlapping single particle Cherenkov events to HIJING background

  27. PID performance: ID range Lower limit: Cherenkov threshold Upper limit: 3s separation 19/10/09 ALICE Upgrade Forum 30

  28. Simulation results: Pb-Pb background HIJING generator dNch/dh = 4000 at mid rapidity: maximum foreseen High-pT Physics at LHC, 17 March 2008 G. Volpe

  29. Option I; PID for π One particle / event With Central Pb+Pb HJ as a background ~ 15 % Particle was identified asπ (Blue), k - Red, p – Green, No PID - black

  30. Option I; PID for K One particle / event With Central Pb+Pb HJ as a background Particle was identified asπ (Blue), k - Red, p – Green, No PID - black

  31. Option I; PID for p One particle / event With Central Pb+Pb HJ as a background Particle was identified asπ (Blue), k - Red, p – Green, No PID - black

  32. Proposed option II. • Three detectors in the same space available • RICH with CF4 and windowless GEM+CsI pad read-out • Gas micro-pattern tracking detector with pad-readout. • Threshold Cherenkov detector with C4F10 + quartz window + GEM pad-readout

  33. Option II; Two detectors (RICH with CF4 and Cherenkov with C4F10) plus additional tracking detector. MWPCh or GEM detector with CsI and 5x5 mm2 pads SiO2 Window C4F10 gas 70 cm Tracking Detector, 5x5 mm2 pads Spherical UV Mirror CF4 gas 35 cm GEM detector with CsI and 5x5 mm2 pads It is useful for high Pt trigger Particle track & UV photons

  34. Option II; PID for π One particle / event With Central Pb+Pb HJ as a background Particle was identified asπ (Blue), k - Red, p – Green, No PID - black

  35. Option II; PID for K One particle / event With Central Pb+Pb HJ as a background Particle was identified asπ (Blue), k - Red, p – Green, No PID - black

  36. Option II; PID for p One particle / event With Central Pb+Pb HJ as a background Particle was identified asπ (Blue), k - Red, p – Green, No PID - black

  37. Option II; detector response ( cluster charge) for UV photons and MIPs; and High Pt trigger possibility Three reconstructed MIP hits were matched as a track, Line fit in (XY) and (RZ) DCA to (0., 0.) in (XY), cm Cluster charge, pC Pt, GeV/c Blue – UV photons; Red – MIPs Green – No FEE Noise • With cuts selected to get 98% efficiency for “one high Pt track / event” • for Central HIJING event the probability to get false trigger • ( “DCAxy < 15. cm”) is smaller than 4% / detector

  38. Beam tests of CsI coated TGEM (Nov 2009) • 10x10 cm prototype layout: • Triple Thick GEM with CsI coated top element, CaF2 window Cherenkov radiator, pad readout • Goals of the tests: • Gas mixture % optimization (Ne/CH4) • HV settings/gain optimization • FEE setting for readout of e- induced signal • Response of CsI layer evaporated on TGEM • Prove working principle: simultaneous detection • of single UV photons (Cherenkov radiation) and MIPs Beam 4 mm CaF2 window Cherenkov light 40mm Drift mesh Drift gap 10mm CsI layer 3mm 3mm 4.5mm R/O pads 8x8 mm2 Front end electronics (Gassiplex + ALICE HMPID R/O + DATE + AMORE)

  39. Cherenkov blobs e- e+ qpair opening angle ~ 1 m The PHENIX Hadron Blind Detector (HBD) • 24 Triple GEM Detectors • (12 modules per side) • Area = 23 x 27 cm2 • Mesh electrode • Top gold plated GEM for CsI • Two standard GEMS • Kapton foil readout plane • One continuous sheet per side • Hexagonal pads (a = 15.6 mm) Proximity Focused Windowless Cherenkov Detector Radiator gas = Working gas Gas volume filled with pure CF4 radiator

  40. Concluding Slides Detector design for best possible hadron PID *) • Must include: • dE/dX • ToF • TRD • Cherenkov and RICH with liquid, aerogel, and gas radiator working inside of B-field (CsI + GEMs, TGEMs, MWPCH). • High quality track finding and momentum reconstruction • Trigger *) based on working detectors and R&D results at RHIC and LHC

  41. Performance of Hadron PID π/K/p dE/dx + ToF A1 A1+A2+RICH π RICH A1+ToF A1+A2 K RICH ToF A1+A2 p RICH 1. 2. 3. 4. 5. 6. 7. 8. 9. 10 12. 14. 16 18. P, GeV/c A1, A2 – aerogel Cherenkov detectors with different n-index And a good quality e, μ, -identification

  42. Conclusion Cherenkov Detectors at RHIC and LHC are working and will be used in upgraded and new experimental setups.

  43. STAR Upgrades R&D Proposal • The broad strategy for upgrading the STAR Detector includes: “Improve the high-rate tracking capability and develop the technology for eventual replacement of the Time Projection Chamber.” STAR tracking issues that need to be addressed and solved ( at upgraded RHIC luminosity ) • TPC Event pile up • TPC Space Charge • Additional tracking, PID Detectors • Trigger power improvement • Increase data rate

  44. Possible solution. Future STAR tracking / PID set up (TPC replacement ) • 16 identical miniTPC’s with GEM readout; “working” gas: fast, low diffusion, UV transparent. dR = 20-50 cm, dZ=+/-45 cm, maximum drift time – 4.5 μs. with enhanced e+/- PID capability (Cherenkov Detector in the same gas volume) • 3-4 layers of Pad Detectors on the basis of GEM technology: needed space resolution, low mass, not expensive, fast (∆t ~ 10 ns ) • Allows consideration to use the space for more tracking ( Forward Direction), PID Detectors (TRD, Airogel Ch, …..)

  45. High precision Vertex Detector( c-, b- decay identification) Highresolution inner vertex detector, better than 10 m resolution, with better than 20m point-back accuracy at the primary vertex. CMOS Active Pixel Sensor (APS) technology – can be very thin, allows some readout to be on same chip as detector. Develop high speed APS technology for second generation silicon replacement (LEPSI/IReS, and LBNL+UC Irvine) Required Areas of development: • APS detector technology • Mechanical support and cabling for thinned silicon • Thin beam pipe development • Calibration and position determination • Data stream interfacing

  46. Fast, Compact TPC with enhanced electron ID capabilities CsI Photocathode 100 MeV e- 2 x 55. cm 20 cm 55 cm 70 cm 16 identical modules with 35 pad-rows, double (triple) GEM readout with pad size: 0.2x1. cm². Maximum drift: 40-45 cm. “Working” gas: fast, low diffusion, good UV transparency .

  47. STAR tracking, proposed variant Pad Detector III Pad Detector II Pad Detector I Beam Pipe and Vertex Detectors miniTPC y ToF R EMC x z Magnet

  48. HBD PID, step 1 (for “low” Pt tracks) Pad Det with CsI (GEM ?!) • For all found in miniTPC tracks dE/dX analysis/ selection were done; • then some number of tangents to selected tracks were calculated and “crossing” points with Pad Det (if it was possible) were saved, • “search corridor” was prepared. y x Z, cm φ, rad

  49. HBD PID, step 2, (for “high” Pt e+/-) • For tracks that crossed Pad Detector I, a matching procedure was done ( TPC track – Pad Det Hit ), and an analysis took place to check the number of UV-photons hits inside of cut values (which are the function of Pt, Pz) e- miniTPC hits Pad Det I hits

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