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Results from STAR and status of the FTPC. María J. Mora Corral. Project Review 2002 MPI. Forward TPC group. Permanent Physicists V. Eckardt, P. Seyboth Computing J. Seyboth, M. Vidal Postdocs M. Oldenburg (1/2003), M.J. Mora Corral Ph.D. Students J. Putschke, F. Simon Diploma Student - PowerPoint PPT Presentation
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Results from STARand status of the FTPC
María J. Mora Corral
Project Review 2002 MPI
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
2
Forward TPC group• Permanent Physicists
– V. Eckardt, P. Seyboth• Computing
– J. Seyboth, M. Vidal• Postdocs
– M. Oldenburg (1/2003), M.J. Mora Corral• Ph.D. Students
– J. Putschke, F. Simon• Diploma Student
– P. MaierbeckLots of help from MPI technical and computing support
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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Outline
• Heavy ion collisions at RHIC• The STAR experiment• Highlights from STAR
– Particle ratios– Anisotropic flow– Suppression at high pT
• Forward TPC from MPI-München• Summary and outlook
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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How does matter look at high density and temperature?
High Density QCD Matter inLaboratory Determine its properties
QCD Prediction: Phase Transitions Deconfinement to QGP Chiral symmetry restoration
Relevance to other research areas? Quark-hadron phase transitionin early Universe Cores of dense stars High density QCD
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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The Relativistic Heavy Ion Collider
STARPHENIX
PHOBOS BRAHMS
RHIC
Design Performance Au + Au p + pMax snn 200 GeV 500 GeVL [cm-2 s -1 ] 2 x 1026 1.4 x 1031
Interaction rates 1.4 x 103 s -1 6 x 105 s -1
Ions: A = 1 ~ 200, pp, pA, AA, AB
two superconducting rings3.83 km in circumference
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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Time of Flight Patch
The STAR experimentSTAR uses the world’s largest Time Projection Chamber
Trigger Barrel +
Ring Imaging Cerenkov
Zero Degree Calorimeter
1st year detectors (2000)Au+Au @ 130 AGeV
EMCal Barrel +
Forward Time Projection Chamber
2nd year detectors(2001-2002)Au+Au and p+p @ 200 AGeV
Silicon Vertex Tracker +Silicon Strip Detector
Photon Multiplicity Detector
3rd year detectors(2003)d+Au and p+p @ 200 AGeV
End Cap EMC
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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a STAR event …One of the first Au+Au events at CM energy of 200 AGeV
• Efficient tracking and momentum measurement• Particle identification: dE/dx invariant mass topologicalp, p-bar, +, -, K+, K- , -bar-bar-bar…
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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p-bar/p ratios
YpbarYp
Ypair
Ypair YTr0.8
YpairYTr
4
• Pair-production increases with collision energy.
• Mid-rapidity region is not yet baryon-free!
• Pair-production is larger than baryon transport.
• 80% of protons from pair production.
______
STAR preliminary
Early Universe p-bar/p ratio
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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Particle ratios
• STAR excels in particle yields study! (and good agreement between different experiments ).
• Evidence for thermal equilibrium at high temperature and density.• RHIC increasing s: same temperature, decreasing baryon density.
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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Azimuthal anisotropy (flow)
STAR Preliminary 130GeV
Fourier analysis
1+2v1cos(lab-plane)+2v2cos2(lab-plane)+…
Non-central collisions: spatially asymmetric initial state
lab-plane
Anisotropic flow
Final state azimuthal momentum asymmetry
Interactions
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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STAR Preliminary 130GeV
Elliptic flow
• At moderate pT the elliptic flow is well described by hydro models, even for different particles.
• At high pT the trend can be reproduced including hard scattering with an energy loss.
PRL 86, 402 (2001) & nucl-ex/0107003
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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High pT particles and suppression• Jets and mini-jets at s = 200GeV
– 30-50 % of particle production– High pt leading particles– Azimuthal back-to-back correlations
• Extend into perturbative regime– Calculations reliable (?)
• Scattered partons propagate through matter &radiate energy (dE/dx ~ x) in colored medium – Interaction of parton with partonic matter– Suppression of high pt particles: “jet quenching”– Suppression of back-to-back correlations– Creation of event-plane correlations
hadrons
q
q
hadronsleadingparticle
leading particle
schematic view of jet production
QGP
Vacuum
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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High pT particle suppression
Evidence for hadron suppression at high pt
Partonic interaction with matter? dE/dx?
Preliminary
• Scale Au-Au data by the number of binary collisions
• Compare to UA1pp reference data measured at 200 GeV
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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The forward TPC
• 2 FTPCs with 1.20 m length. • Rinner = 7.73 cm, Router = 30.05cm.• Covering || region 2.5-4.0.• 10 padrows in the beam direction with 6
azimuthal sectors each.• Efield radial, 240-1400V/cm, beam.• B field =0.5 T, || beam.• Gas mixture 50%Ar 50%CO2.
• Extend STAR charged particle acceptance into region 2.5 < || < 4.0.
• Study charged particle and net proton (h+-h-) spectra.
• Anisotropic flow.• Ks
0 and production.• Fluctuations of <pT>.• DCC search.
Bfield
Efield
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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The forward TPC: What is new?PROBLEM: Region with high particle multiplicity achieve high two track separation
SOLUTION: Apply a radial electric field ( magnetic field)
COMPLICATIONS: Drift velocity not constant. Drift path curved due to ExB deflection.
vD(r) and D(r) need to be known with high accuracyWe use MAGBOLTZ calculations
Very sensitive
to calibration
co n st)()(v
co n st)(vv1
rFBrqFBE
rr
E
D
DD
l e )L o r e n t z a n g(
)(
r)(v
)(
L
D
0
00
r
r
LD
r
r
r
rD
d rrr
rd r
d trT
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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From signals to tracksCharge signals (pad, time)
Cluster finder +Cluster unfolding
Hits (pad, time)
Magboltz drift maps
Space points (r,)
Track finder
Track (space point collection from same
particle)
Vertex extrapolation
Laser tracks+Drift Vel. Monitor
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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Example: Charge step sensitivity
Sector numberR
adiu
s st e
p (c
m)
Drift time
Charge-step (maximum drift time of the electrons) shows a hardware sector wise structure
azimuthal dependence cluster position!
Sensitive to small (200 m) inaccuracy in detector geometry which leads to 2mm fluctuation!!
200m shift
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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FTPC raw multiplicity vs TPC,CTB
no quality cuts applied on FTPC tracks (primaries & secondaries)
Good correlation between FTPCand TPC, CTB multiplicity.
FTPC multiplicity
TPC
mul
tiplic
ity
FTPC multiplicity
CTB
mul
tiplic
ity
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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Raw charged particle spectra
pt [GeV]
1/N
even
t*dN
/dp t
1/
Nev
ent*d
N/d
Efficiency and acceptance calculations have startedto extract corrected charged particle spectra !
pT distribution distribution
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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FTPC event plane correlations
• Elliptic flow (v2) visible in the FTPCs
• Directed flow (v1) signal is very small
firstharmonic
secondharmonicV1= V2=
FTPCEast/FTPCWestFTPCEast/FTPCWest
FTPCt/TPC
v2
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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FTPC elliptic flow
• Not final results• Elliptic flow decreases with pseudorapidity?
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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Summary and outlook• Exciting new results from STAR year II
– Net baryons have continued to decrease with increasing energy, although there’s still some stopping/baryon transport to ycm.
– Hadronic particle yields reveal a statistical behaviour.– Suppression of particles and azimuthal correlations at high pT
indicate parton energy loss in the medium.
• First year with the FTPC– 90K minBias, 1.6M central Au+Au events and 15M p+p events
collected.– Radial drift and ExB effects make calibrations challenging.– Spectra and anisotropic flow studies in progress.
• Plans for next Run (January-May 2003)– 10 weeks d+Au and 3 weeks polarized p+p collisions.– Improved laser and DV calibrations.
• Continuation of data taking in 2003-2004
M.J. Mora Corral Project Review MPI München, 16/Dec/2002
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Efficiencies
• First approach to efficiencies with simulations.
• For final efficiencies we need to embed a simulated particle into real event.