Particle identification.RHIC, LHC (ALICE)(status and future) N.Smirnov. Physics Department, Yale University

JLab, Detector workshop, June 4-5, 2010.

STAR Detector2 m2 mB = 0.5 T

ALICE Detector *ITSTPCTRDTOFPHOSHMPIDEMCAL

STAR; dE/dx at low pTOn-line TPC track reconstructionTime Projection Chamber: STAR: 45 padrow, 2 meters (radius), s(dE/dx)8.2%, ALICE: 160 padrow, 2.5 meter (radius), (dE/dx) (5.8-7.)% -1

PiD, Topology and Mass Reconstruction (STAR)Topology analysis (V0s,Cascades, -conversion, kink-events)limitation in low pT, and stat.

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 (). -- GEANT3, detail and careful detector response simulation

*) All details can be found: -- H. Bichsel, NIM A562 (2006) 154 -- http://faculty.washington.edu/hbichsel/

Detector response simulationGEANT3 was used to describe experiment geometry as realistic as possible, and to simulate a particle track.One particle per event, 0.5 T magnetic field, decay and nuclear interaction OFF.For each TPC pad-row input and output points in space (Local Coordinate System) and particle momentum were saved (HIT).For each HIT number of ionization electrons and there position in space were simulated including long range (delta-) electrons using energy losses approach stressed earlier.

Detector response simulationFor each electron: -- drift, absorption, diffusion, anode wire selection steps were simulated. -- Gas amplification (Polya distribution). -- An induction charge on read-out pads was calculated.

FEE response using an arrival time for each electron, noise and cross-talk parameters.Cluster finding (efficiency parameter); q in a cluster.Truncated procedure.dE/dX and PID analysis in N for {log(q / )/+9}.

STAR TPC; experiment simulation comparison (dE/dX and PID analysis in N for {log(q / )/+9}.)

Data from O. Barannikova, Proc. 21st Winter Workshop on Nuclear Dynamics(2005). Simulation: Try to be ACAP with number ofHits / track; and use the sameTruncated approach.NppKK

STAR TPC; experiment simulation comparison Pt, GeV/c (N, K - N, ) (N, p - N, ) { 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

Simulation result for ALICE TPC;the same approach, but 90% cluster finding efficiency and optimal truncated proceduredE/dX as a function of dE/dX as a function of momentumP, GeV/c K p

ALICE TPC; PiD performance (on a track level)Particle momentum 4. GeV/cNpKProton identification:Efficiency purityCut parameterFor 70% efficiency 70% purity

ALICE TPC; PiD performance (on a track level)Particle momentum 10. GeV/cpKNProton identification:Efficiency purityCut parameterFor 70% efficiency 70% purity

ALICE TPC; PiD performance (on a track level)NParticle momentum 15. GeV/cpKProton identification:Efficiency purityFor 70% efficiency 70% purityCut parameter

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.

STAR Detectorsr ~ 235cm, s~1.1m2|h|

Charged particle through radiatorMIP and photons detection3) Ring reconstructionRICH IdentificationRICH PID range:1 ~3 GeV/c for Mesons1.5 ~4.5 GeV/c for BaryonsSTAR preliminaryLiquid C6F14Cluster charge, ADC counts, experimental data4) Response simulation

Cherenkov distribution and Fitting: integrated methodCherenkov angle distribution in momentum bins 3 Gaussians fit:a 8 (= 9-1 constraint) parameters.constraint: integral = entries.fixing parameters with simulationa Separate species for each momentum slice:

Identified particle pT spectra 9 such detectors are working in ALICE

Read out pad size3.15cm6.3cmGap: 60.22mm

95% C2H2F4 5% Iso-butaneMultigap Resistive Plate Chamber MRPC Technology developed at CERN3800 modules, 23,000 readout chan. to cover TPC barrelMulti-gap Resistive Plate Chamber TOFr: 1 tray (~1/200), s(t)=85ps

TOF R&D Accomplished in FY03-04

HV was on for the entire run no failuresSF6 is NOT required in the gas mixNoise rate ~200Hz from OR of 72 chan.TPC track matching done Calibrations (t-zero, slewing, TDC nonlinearity, ) are all performed 85 ps MRPC timing resolution demonstrated for a small system in the RHIC/STAR environment95% MRPC efficiency demonstrated in the RHIC/STAR environmentPID capability demonstrated Electron tagging demonstratedPhysics publication submitted

ToF + dE/dX: e / hadron PIDElectron identification: TOFr |1/-1| < 0.03 TPC dE/dx electrons!!!electronsnucl-ex/0407006

ALICE experiment 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 (15 GeV/c).

High-pT Physics at LHC, 17 March 2008 G. Volpewith TOF data

Definition of high Pt

Experience from RD26; HMPID R&D, construction and utilization in STAR and ALICEExperience 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 simulationGas quality and Index of refraction controls

ALICE VHMPID design constraintsCharged hadrons (p, K, p) identification in 10 - 30 GeV/c Focusing RICH with gaseous radiatorHigh Pt triggerLimited available space in ALICEFilling factor (acceptance), radiator length Limited time for R&D and (possibly) detector constructionHMPID heritage and know-how: CsI, MWPC, FEE,

07/05/2010A. Di Mauro - RICH2010, Cassis *

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

07/05/2010Detector principle schemeFocusing RICH, C4F10 gas radiator L~ 80 cmPhoton detector a la HMPID, baseline option: MWPC with CsI pad (8x8 mm) segmented photocathode; alternative: CsI-TGEM or GEMSpherical (or parabolic) mirror, composite substrate, Al/MgF2 coatingFEE based on HMPID Gassiplex chip, analogue readout for localization via centroid measurement *A. Di Mauro RICH2010, Cassis

Integration in ALICE07/05/2010A. Di Mauro RICH2010, Cassis*Free slot for prototype~ supermodule7% acceptance wrt TPC12% wrt TPC in | | < 0.5 (jet fully contained)TPCTRD

Expected performanceThe 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

Signal(GeV/c)Absence of signal(GeV/c)p4-16K11-16p18-3011-18

PID performance: ID range19/10/09*ALICE Upgrade ForumLower limit: Cherenkov thresholdUpper limit: 3s separation

Signal(GeV/c)Absence of signal(GeV/c)p4-24K11-24p18-3811-18

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

Option I; PID for One particle / eventWith Central Pb+Pb HJ as a backgroundParticle was identified as (Blue), k - Red, p Green, No PID - black~ 15 %

Option I; PID for KOne particle / eventWith Central Pb+Pb HJ as a backgroundParticle was identified as (Blue), k - Red, p Green, No PID - black

Option I; PID for pOne particle / eventWith Central Pb+Pb HJ as a backgroundParticle was identified as (Blue), k - Red, p Green, No PID - black

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

Option II; Two detectors (RICH with CF4 and Cherenkov with C4F10) plus additional tracking detector.Spherical UV Mirror CF4 gasC4F10 gas SiO2 WindowTracking Detector, 5x5 mm2 pads GEM detector withCsI and 5x5 mm2 pads MWPCh or GEM detector withCsI and 5x5 mm2 pads70 cm35 cmParticle track & UV photonsIt is useful for high Pt trigger

Option II; PID for One particle / eventWith Central Pb+Pb HJ as a backgroundParticle was identified as (Blue), k - Red, p Green, No PID - black

Option II; PID for KOne particle / eventWith Central Pb+Pb HJ as a backgroundParticle was identified as (Blue), k - Red, p Green, No PID - black

Option II; PID for pWith Central Pb+Pb HJ as a backgroundOne particle / eventParticle was identified as (Blue), k - Red, p Green, No PID - black

Option II; detector response ( cluster charge) for UV photons and MIPs; and High Pt trigger possibility

Cluster charge, pC Blue UV photons; Red MIPsGreen No FEE NoiseThree reconstructed MIP hits werematched as a track,Line fit in (XY) and (RZ) DCA to (0., 0.) in (XY), cmPt, GeV/cWith 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

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 detectionof single UV photons (Cherenkov radiation) and MIPs

The PHENIX Hadron Blind Detector (HBD)Proximity Focused Windowless Cherenkov Detector

Radiator gas = Working gasGas volume filled with pure CF4 radiator24 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)

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

1. 2. 3. 4. 5. 6. 7. 8. 9. 10 12. 14. 16 18.P, GeV/c /K/p dE/dx + ToFp A1A1+A2+RICHRICH KA1+ToFA1+A2RICH ToFA1+A2RICHPerformance of Hadron PIDAnd a good quality e, , -identificationA1, A2 aerogel Cherenkov detectors with different n-index

Conclusion

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

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 upTPC Space ChargeAdditional tracking, PID DetectorsTrigger power improvementIncrease data rate

Possible solution. Future STAR tracking / PID set up (TPC replacement )

16 identical miniTPCs with GEM readout; working gas: fast, low diffusion, UV transparent. dR = 20-50 cm, dZ=+/-45 cm, maximum drift time 4.5 s. 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, ..)

High precision Vertex Detector( c-, b- decay identification)High resolution 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 technologyMechanical support and cabling for thinned siliconThin beam pipe developmentCalibration and position determinationData stream interfacing

Fast, Compact TPC with enhanced electron ID capabilities100 MeV e-20 cm55 cm70 cmCsI Photocathode2 x 55. cm16 identical modules with 35 pad-rows, double (triple) GEM readout with pad size: 0.2x1. cm. Maximum drift: 40-45 cm. Working gas: fast, low diffusion, good UV transparency .

STAR tracking, proposed variant

Pad Detector IIIPad Detector IIPad Detector IBeam Pipe andVertex DetectorsminiTPCToF EMCMagnetyxRz

HBD PID, step 1 (for low Pt tracks)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.Pad Det with CsI (GEM ?!)yxZ, cm, rad

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 hitsPad Det I hits

Pad Detector response simulation, and e+/- PIDCentral Au+Au event (dNch/dY~750), simulated using HIJING event generator with full scale detectors response simulation,Reconstructed hit positions, Z-Rphi, cmMIP blue pointsUV red points1640 MIP hits 8200 act. Pads790 UV hits 1185 act. PadsPad size = 0.6x0.6 cm2Number of pads = 133632Occupancy = 7.0%R, cmZ, cm

HBD performance (preliminary) For central HIJING events, CH4, 0.5 T: the lepton PID efficiency ( all found tracks in TPC) 90.8%. The number of wrong hadron identifications 1.5 tracks/event. Number of reconstructed UV photons/track ( 9 or more TPC hits )

Mean 7.4RMS 2.83