Measurements of high-pT neutral mesons in = 200 GeV Au+Au and Cu+Cu Collisions at RHIC-PHENIX
What have we learned from RHIC, So far? RHIC has taken data in: 2001: AuAu (130GeV) 2002: AuAu,...
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Transcript of What have we learned from RHIC, So far? RHIC has taken data in: 2001: AuAu (130GeV) 2002: AuAu,...
What have we learned from RHIC , So far?
RHIC has taken data in:2001: AuAu (130GeV)2002: AuAu , pp(200 GeV)2003: pp, dAu (200 GeV)
Any nucleus on any other.Top energies (each beam):
100 GeV/nucleon Au-Au.250 GeV 2 counter-circulating rings, 3.8 km circumferencepolarizedpolarized p-p.
PHOBOS Detector 2003
SPECTRIG
T0
T0
mini-pCal
pCal
i. Moved TOF walls back
• 5 m from interaction point
ii. New on-line high pT Spectrometer Trigger
iii. New “time-zero” (T0) Cerenkov detectors
• On-line vertexing and ToF start time
iv. Forward proton calorimeters on Gold and Deuteron sides
v. DAQ upgrade (x10)
95° 30°
30°15°
2.3°
STARSTAR
BRAHMS
PHENIX
Russia:MEPHI - MoscowLPP/LHE JINR - DubnaIHEP - Protvino
U.S. Laboratories:ArgonneBerkeleyBrookhaven
U.S. Universities: UC BerkeleyUC DavisUC Los AngelesCarnegie Mellon Creighton UniversityIndiana UniversityKent State UniversityMichigan State UniversityCity College of New YorkOhio State UniversityPenn. State UniversityPurdue UniversityRice UniversityTexas A&MUT AustinU. of Washington Wayne State UniversityYale University
Brazil: Universidade de Sao Paulo
China: IHEP – BeijingIMP - LanzouIPP – WuhanUSTCSINR – ShanghaiTsinghua University
Great Britain: University of Birmingham
France:IReS StrasbourgSUBATECH - Nantes
Germany: MPI – MunichUniversity of Frankfurt
India:IOP - BhubaneswarVECC - CalcuttaPanjab UniversityUniversity of RajasthanJammu UniversityIIT - BombayVECC – Kolcata
Poland:Warsaw University of Tech.
The STAR Collaboration
High Density QCD Matter in Laboratory
Determine its properties
QCD Prediction: Phase Transitions
Deconfinement to Q-G Plasma
Chiral symmetry restoration
Relevance to other research areas?
Quark-hadron phase transition in early Universe
Cores of dense stars
High density QCD
Phases of QCD
Preliminary sNN = 200 GeV
Uncorrected
participants
spectators
peripheral (grazing shot)
central (head-on) collisionCentrality classes based on mid-rapidity multiplicity
Npart (Wounded Nucleons) ~ soft production
Nbin ~ hard processes
Centrality and Participants in HI
5% central
15% Central
Au AuZDC ZDC
•Symmetric Zero Degree Calorimeters
•Central Trigger Barrel
Triggering Capabilities
Understanding “Bulk” MatterStudying Matter:
– Global Observables Nch, ET, pT
, S, …
– Particle Yields & Ratios
Tch, B, S, …
– Particle Spectra Tfo, flow, stopping,
…– Correlations– … and all that in pp,
pA, AA
STAR preliminary
99.5%
Rapidity Density600 1200
PHOBOS Central Au+Au (200 GeV)
Compilation by K. Eskola
• Multiplicity at low end of range– But: Energy density 30x nuclear
matter
• Most models didn’t do so wellPHOBOS multiplicity papers:
Phys. Rev. Lett. 85 , 3100 (2000)
Phys. Rev. Lett. 87, 102303 (2001)
Phys. Rev. C 65 , 31901R (2002)
Phys.Rev. Lett. 88 , 22302 (2002)Phys. Rev. C 65 , 061901R (2002) nucl-ex/0210015, PRL in Pressnucl-ex/0301017, subm. to PRL
Particle Production
RHIC: Nch at mid-rapidity
Consistency of RHIC resultsPHENIX: PC, STAR: TPC
PHOBOS: Si BRAHMS: Si & Scint.
PHENIX & STARpreliminary
Ratio R(200/130):BRAHMS: 1.14 0.05PHENIX: 1.17 0.03PHOBOS: 1.14 0.05STAR: 1.19 (no sys. yet)
Nch(sNN) – Universality of Total Multiplicity?
• pQCD e+e- Calculation
)/exp( sBsch CAN
Total charged particle multiplicity / participant pair
Accidental, trivial? Is plain parton fragmentation all there is in AA above s ~ 20 GeV?
(A. Mueller, 1983)
2/sseff
Same for all systems at same s(seff for pp)
Nch: Centrality Dependence at RHIC (SPS)
_pp
PHOBOS Au+Au ||<1
19.6 GeVpreliminary
130 GeV
200 GeV
Au+Au
(preliminary)
Everything counts:• Nch|=0 described nicely by KN (hard + soft)• Nch scales with Npart
collpp
partpp
Nxn
Nnx
d
dN
2
)1(
Rapidity Spectra: Boost-Invariance at RHIC ?
M. Baker (PHOBOS)
D. Ouerdane (BRAHMS)
1cosh)/(
cosh)/(),( :Jacobian
22
mp
mpp
y
ET/ Nch from SPS to RHIC
Independent of energyIndependent of centrality
PHENIX preliminaryPHENIX preliminary
Surprising fact: SPS RHIC: increased flow, all particles higher pTstill ET/ Nch changes very littleDoes different composition (chemistry) account for that?
Ratios, Ratios, Ratios ….• Huge amount of results from all 4 RHIC experiments:• systematic studies of: -/+, K-/K+, p/p/ ,/,/,
/p, K/ , /, /h, K, K*/K, …– many as function of pT, Npart
– at s of (20), 130, and 200 GeV– with and without feed-down correction ()
• BRAHMS large y coverage and reach to high pT
• PHENIX reach to high pT
• STAR multi-strange baryons
NEW: Rapidity dependence of ratios at RHIC
BRAHMS 200 GeV
At mid-rapidity:Net-protons: dN/dy 7proton yield: dN/dy 29 ¾ of all protons from pair-production
p/
• Proton yield is comparable with pions @ 2 GeV in central collisions, less in peripheral
Central
Peripheral
Statistical Model: First Look at AuAu @ 200 GeV
Predictions:phenomenologically: B ~ 1.3 GeV (1+s/4.5 GeV)-1
assume unified freeze-out condition: E/N ~ 1.1 GeV T
Statistical Models: from AGS to RHIC
Fit by Beccatini using total yields from NA49hadron gas fit with partial strangeness saturation
Different implementation ofstatistical model (Kaneta/Nu,Beccatini, PBM et al., …)
Fact: all work well at AGS, SPS and RHIC
Slight variations in the models, but roughly:
Tch [MeV] B [MeV]
AGS 125 540
SPS 165 250
RHIC 175 30
Does the success of the modeltells us we are dealing indeed with locally chemically equilibrated systems? this+flow If you ask me YES!
Anisotropic flow from AGS to RHIC
Outline:1. Directed flow
(techniques, models, results)2. Elliptic flow
(techniques, models, results)3. Elliptic flow at high pt’s.4. Open questions
...) φ) ( v ) (φ v (dy dpN d
dφ dy dpN d
t t
2 2 2 121
2 1
2 3
cos cosπ
Directed flow Elliptic flow
Anisotropic flow correlationswith respect to the reaction plane
X
Z b
XZ – the reaction plane
Picture: © UrQMD
What flows and when?
<pT> prediction with Tth
and <> obtained from blastwave fit (green line)
<pT> prediction for Tch = 170 MeV and <>=0pp no rescattering, no flowno thermal equilibrium
STAR
preliminaryF. Wang
and appear todeviate from commonthermal freeze-out Smaller elast? Early decoupling from expanding hadronic medium? Less flow?What’s about partonic flow?