Particle identification in STAR (status and future)
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Particle identification in STAR(status and future)
R.Majka, N.Smirnov. Yale University
(for the STAR experiment)
5th International Workshop on Ring Imaging Cherenkov Detectors. Playa del Carmen, Mexico, Nov. 30 – Dec. 5, 2004.
STAR Detector at RHIC, BNL was designed primarily for measurements of hadron production over a large solid angle, featuring detector systems for high precision tracking, momentum reconstruction and particle identification. The hadron identification was done using dE/dX data, and topological identification of decaying particles by secondary vertices finding and/or reconstructing invariant masses.The CERN-STAR RICH Detector extended the particle identification capabilities for charged hadrons at mid-rapidity. ToF Detector (MRPC technology) construction and installation is in a progress. First results are available and will be presented. The simulated performance of a fast, compact TPC in combination with a Cherenkov CsI Pad Detector for enhanced e+/- identification will be discussed as a possible variant of a STAR upgrade
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STAR DetectorSTAR Detector
2 m
2 m
B = 0.5 T
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dE/dx at low pT
On-line TPC track reconstruction
Time Projection Chamber: 45 padrow, 2 meters (radius), dE/dx)8%, -1<
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PiD, Topology and Mass Reconstruction
• Topology analysis (V0s,Cascades, -conversion, “kink”-events…)
• limitation in low pT, and stat.
TPC
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Statistical Model
Strangeness Enhancement
Resonance Suppression
STAR Preliminary
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r ~ 235cm, s~1.1m2
||<0.3 and
CERN-STAR Ring Imaging Čerenkov Detector
STAR Detectors
Prototype (ALICE, small acceptance)
STAR Time Projection Chamber
run II Au+Au @ 200 GeV
dE/dx
pion
s
kaons
pro
tons
deute
rons
electrons
dE/dx PID range: (dE/dx) = .08]
p ~ 0.7 GeV/c for K/
~ 1.0 GeV/c for p/x
||<1.5 and
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1) Charged particle through radiator2) MIP and photons detection
3) Ring reconstruction
RICH Identification
RICH PID range:1 ~3 GeV/c for Mesons1.5 ~4.5 GeV/c for Baryons
STAR preliminaryLiquid C6F14
Cluster charge, ADC counts, experimental data
4) Response simulation
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Cherenkov distribution and Fitting: integrated method
Cherenkov angle distribution in momentum bins
3 Gaussians fit: 8 (= 9-1 constraint) parameters.constraint: integral = entries.fixing parameters with simulation
pions
kaonsprotons Separate species for each momentum slice:
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Identified particle pT spectra
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Read out pad sizeRead out pad size ::3.15cm×6.3cm3.15cm×6.3cm
gapgap :: 6×0.22mm6×0.22mm
95% C95% C22HH22FF44
5% Iso-butane5% Iso-butane
Multigap Resistive Plate Chamber Multigap Resistive Plate Chamber MRPCMRPC Technology developed at CERN Technology developed at CERN
3800 modules, 23,000 readout chan. to cover TPC barrel3800 modules, 23,000 readout chan. to cover TPC barrel
Multi-gap Resistive Plate Chamber TOFr: 1 tray (~1/200), (t)=85ps
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Hadron identification: STAR Collaboration, nucl-ex/0309012
ToF + dE/dX: “Hadron-Blind Detector”
Electron identification: TOFr |1/ß-1| < 0.03 TPC dE/dx electrons!!!
electrons
nucl-ex/0407006
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carbon composite (75 m)Young’s modulus 3-4 times steel
aluminum kapton cable(100 m)
silicon chips(50 m)
21.6 mm
254 mm
Mechanical and Mechanical and integration issues are integration issues are being addressed:being addressed:
Existing SiliconExisting Silicon
Two Two Layers of Layers of APSAPS
Integration volume and rapid Integration volume and rapid insertion/removal being studied insertion/removal being studied using modern 3-D modeling using modern 3-D modeling tools.tools.
Features of First Generation Design:Features of First Generation Design:
• 2 layers2 layers
• Inner radius ~1.8 cmInner radius ~1.8 cm
• Active length 20 cmActive length 20 cm
• Readout speed 4 ms (generation 1) Readout speed 4 ms (generation 1)
• MIMOSA-5 MIMOSA-5 LEPSI/IReS MIMOSTAR LEPSI/IReS MIMOSTAR
• Number of pixels 130 M ( 20 x 20 Number of pixels 130 M ( 20 x 20 μμm² pixel size)m² pixel size)
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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
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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, …..)
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100 MeV e-
20 cm
55 cm70 cm
CsI Photocathode
Fast, Compact TPC with enhanced electron ID capabilities
2 x 55. 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 .
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STAR tracking, proposed variant
Pad Detector III
Pad Detector II
Pad Detector I
Beam Pipe andVertex Detectors
miniTPC
ToF
EMC
Magnet
y
x
R
z
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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 ?!)
y
xZ, cm
φ, rad
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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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Pad Detector response simulation, and e+/- PID
Central Au+Au event (dNch/dY~750), simulated using HIJING event generator with “full scale” detectors response simulation,Reconstructed hit positions, Z-Rphi, cm
MIP – blue pointsUV – red points
1640 MIP hits 8200 act. Pads790 UV hits 1185 act. PadsPad size = 0.6x0.6 cm2Number of pads = 133632Occupancy = 7.0%
Rφ, cm
Z, cm
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HBD performance (preliminary)
0
200
400
600
800
1000
1200
1400
1 6 11 16 21
N photons
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
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Expression of Interest -
A Comprehensive New Detector at RHIC II
P. Steinberg, T. Ullrich (Brookhaven National Laboratory)
M. Calderon (Indiana University)
J. Rak (Iowa State University)
S. Margetis (Kent State University)
M. Lisa, D. Magestro (Ohio State University)
R. Lacey (State University of New York, Stony Brook)
G. Paic (UNAM Mexico)
T. Nayak (VECC Calcutta)
R. Bellwied, C. Pruneau, A. Rose, S. Voloshin (Wayne State University)
and
H. Caines, A. Chikanian, E. Finch, J.W. Harris, M. Lamont, C. Markert,
J. Sandweiss, N. Smirnov (Yale University)
EoI Document at http://www.bnl.gov/henp/docs/pac0904/bellwied_eoi_r1.pdf
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Comprehensive New Detector at RHIC II
Large magnetic field (B = 1.3T)
- 3.4 < || < 3.4 inside magnet
– Tracking
– PID out to 20 – 30 GeV/c
– EM/hadronic calorimetry
– chambers
– Triggering
4 acceptance
3.5 < < 4.8 forward spectrometer
– External magnet
– Tracking
– RICH
– EM/hadronic calorimetry
– Triggering
• Quarkonium physicsQuarkonium physics• Jet physicsJet physics• Forward low-x physicsForward low-x physics• Global observables in 4Global observables in 4• Spin PhysicsSpin Physics
HCal and -detectors
Superconducting coil (B = 1.3T)
RICH
HC
al &
-d
ets
Aerogel
EM Calorimeter
ToF
Forward spectrometer: ( = 3.5 - 4.8) magnet tracking RICH EMCal (CLEO) HCal (HERA)-absorber|| 1.2
=
1.2
– 3
.5
Central detector (| 3.4)
HCal and -detectors
Superconducting coil (B = 1.3T)
Vertex tracking
RICH
HC
al a
nd
-det
ecto
rs
Aerogel
EM Calorimeter
ToFTracking: Si, mini-TPC(?), -pad chambers
PID: RICH ToF Aerogel
Forward tracking: 2-stage Si disks
Forward magnet (B = 1.5T)
Forward spectrometer: ( = 3.5 - 4.8) RICH EMCal (CLEO) HCal (HERA)-absorber
|| 1.2
=
1.2 – 3.5
Central detector (| 3.4)
SLD magnet
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1. 2. 3. 4. 5. 6. 7. 8. 9. 10 12. 14. 16 18.
P, GeV/c
π/K/p dE/dx + ToF
p
πA1 A1+A2+RICH
RICH
KA1+ToF A1+A2
RICH
ToF A1+A2RICH
Hadron PID
And a good quality e, μ, -identification
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Cherenkov Detectors at RHIC are working and will be used in upgraded and new experimental setups.