Results and Perspectives
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AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Results and Perspectives
Gábor I. VeresEötvös Loránd University, Budapest and
Massachusetts Institute of Technology, Cambridge
for the collaboration
RHIC & AGS Annual Users’ Meeting
June 23, 2005
PHOBOS Workshop talks:George Stephans - Femtoscopy (Tue 6/21)Zhengwei Chai - Multiplicity Fluctuations (Tue 6/21)
PHOBOS Posters by: Abigail Bickley, Richard Hollis, Carla Vale
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Another year of spectacular achievement for RHIC & C-AD THANKS!!!
Run 5 is the most diverse run so far:
• 9 weeks of Cu+Cu at 200 GeV (6 nb-1)
• 2 weeks of Cu+Cu 62.4 GeV (0.25 nb-1)
• 2 days of Cu+Cu 22.5 GeV
• few hours of p+p at 410 and 200 GeV
CuCu@200 CuCu@62.4
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
The Collaboration (June 2005)
Burak Alver, Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Richard
Bindel, Wit Busza (Spokesperson), Zhengwei Chai, Vasundhara Chetluru, Edmundo García,
Tomasz Gburek, Kristjan Gulbrandsen, Clive Halliwell, Joshua Hamblen, Ian Harnarine, Conor
Henderson,
David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta Iordanova, Jay Kane,
Piotr Kulinich, Chia Ming Kuo, Wei Li, Willis Lin, Steven Manly, Alice Mignerey,
Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Corey Reed,
Eric Richardson, Christof Roland, Gunther Roland, Joe Sagerer, Iouri Sedykh, Chadd Smith,
Maciej Stankiewicz, Peter Steinberg, George Stephans, Andrei Sukhanov, Artur Szostak,
Marguerite Belt Tonjes, Adam Trzupek, Sergei Vaurynovich, Robin Verdier, Gábor Veres,
Peter Walters, Edward Wenger, Donald Willhelm, Frank Wolfs, Barbara Wosiek, Krzysztof
Woźniak, Shaun Wyngaardt, Bolek Wysłouch
ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORYINSTITUTE OF NUCLEAR PHYSICS PAN, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGY
NATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGOUNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Outline
• What did we learn in the five years of PHOBOS history?
• Results since the last Users’ Meeting
• Plans and perspectives of PHOBOS
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
5 years of PHOBOS…
Data we took in various runs:
p+p d+Au Cu+Cu Au+Au410 5200 2,3,4,5 3 5 2,4130 162.4 5 455.9 122.5 519.6 2
GeVsystem
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
PHOBOS: number of events on tape…
p+p d+Au Cu+Cu Au+Au410 20200 100 150 400 250130 4.362.4 110 2255.9 1.822.5 2019.6 ~1
GeVsystem
[in millions]
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Evolution of the detector – Pre-run 1: AuAu
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Run 1: Au+Au
AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Run 2: Au+Au and p+p
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Run 3: d+Au and p+p
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Run 4 and 5: Au+Au, Cu+Cu
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Run 4 and 5: p+p
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Run 6…
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Data rate and number of events taken
Run 2
Run 3
Run 4
Run 5All-inclusive count,
Including tests
Continuous DAQ upgrades!
Over a billion events taken
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
The PHOBOS computing architecture… to cope with hundreds of millions of events
Internet
Master
Slave
Slave
Slave
Slave
User
PROOF
CatWeb – data management (650k files, 400 TByte)• Easy www interface to stage HPSSRCF•API for access to functionality from ROOT/PhAT
AnT – Analysis Tree DST format• ROOT Tree based, fast access to subsets of data• Well structured, links hits to tracks etc.
PROOF – Parallel ROOT Facility• Parallel interactive analysis, over x100 speed-up!• Co-exist with regular batch usage
Distributed disks• 100 TByte, fast access • ALL physics data is stored on disks!
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
PHOBOS physics publications
The PHOBOS Perspective on Discoveries at RHICScaling of Charged Particle Production in d+Au Collisions at sqrt(s_NN)=200 GeVCharged antiparticle to particle ratios near midrapidity in p+p collisions at sqrt(s_NN) = 200 GeVTransverse momentum and rapidity dependence of HBT correlations in Au+Au collisions at sqrt(s_NN) = 62.4 and 200 GeVCentrality and pseudorapidity dependence of elliptic flow for charged hadrons in Au+Au collisions at sqrt(s_NN)= 200 GeVEnergy dependence of elliptic flow over a large pseudorapidity range in Au+Au collisions at RHICPseudorapidity dependence of charged hadron transverse momentum spectra in d+Au collisions at sqrt(s_NN)=200 GeVCollision Geometry Scaling of Au+Au pseudorapidity density from sqrt(s_NN) = 19.6 to 200 GeVCentrality dependence of charged hadron transverse momentum spectra in Au+Au collisions from sqrt(s_NN) = 62.4 to 200 GeVParticle production at very low transverse momenta in Au+Au collisions at sqrt(s_NN)=200 GeVPseudorapidity Distribution of Charged Particles in d+Au collisions at sqrt(s_NN)=200 GeVCentrality dependence of charged antiparticle to particle ratios near mid-rapidity in d+Au collisions at sqrt(s_NN)=200 GeVCentrality Dependence of the Charged Hadron Transverse Momentum Spectra in d+Au Collisions at sqrt(sNN)=200 GeV
Charged hadron transverse momentum distributions in Au+Au collisions at sqrt(s_NN) = 200 GeVComparison of the Total Charged-Particle Multiplicity in High-Energy Heavy Ion Collisions with e+e- and pp/pbar-p DataSignificance of the fragmentation region in ultrarelativistic heavy ion collisionsRatios of charged antiparticles to particles near mid-rapidity in Au+Au collisions at sqrt(sNN)=200 GeV
Pseudorapidity and centrality dependence of the collective flow of charged particles in Au+Au collisions at sqrt(sNN)=130 GeV
Centrality Dependence of the Charged Particle Multiplicity near Mid-Rapidity in Au+Au Collisions at sqrt(sNN)=130 and 200 GeV
Energy dependence of particle multiplicities near mid-rapidity in central Au+Au collisions Centrality Dependence of Charged Particle Multiplicity at Midrapidity in Au+Au Collisions at sqrt(sNN)=130 GeV
Charged-particle pseudorapidity density distributions from Au+Au collisions at sqrt(sNN)=130 GeV
Ratios of charged particles to antiparticles near mid-rapidity in Au+Au collisions at sqrt(sNN)=130 GeV
Charged particle multiplicity near mid-rapidity in central Au+Au collisions at sqrt(s) = 56 and 130 AGeV
24 papers, including 12 in Phys. Rev. Letters
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
“White Paper”: summary of PHOBOS results
• We have created a state of matter at RHIC with high energy-density, that is nearly net-baryon free and interacting very strongly.
• Transition to this high-energy state of matter does not create abrupt changes in observables at RHIC energies.
• The data exhibit “simple” scaling behavior and factorization. → suggests strong global constraints and illustrates the importance of the collision geometry in the initial state and the early evolution of the colliding system.
nucl-ex/0410022, Nucl. Phys. A 757, 28
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
High energy density & nearly baryon-free matter
Energy Density Estimate: RHIC > 3 GeV/fm3
Energy density ~6x that of nucleons (20x that of nuclei)
Particle Ratios:Approaching Unity
B at full RHIC energy is a factor ~10 smaller than at SPS.
(Our new result is p+p@200GeV)
A+A
p+p
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Strongly interacting matter…
• Elliptic flow reaches hydro limit• Suppressed high-pT production• No enhanced low-pT production
PHOBOS nucl-ex/0407012…flow
PHOBOS PRC 70, 051901(R)…low-pT
00
0.5
1.0
1.5
RA
A, R
dA
u
Au+Au 0-6%
d+Au 0-20%
…high-pT PHOBOS PRL 91, 072302PHOBOS PRC 70, 061901
d+Au
200 GeV Au+Au, 0-50%
hydro
200 GeV Au+Au
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
200 GeV Au+Au
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Recent theoretical interest at low pT
Phobos 15% data Estimated extrapolation to 5%
data: (Au+Au 15% central
(George Stephans’ talk)J. G. Cramer et al., Phys. Rev. Lett. 94, 102302 (2005)
and PHOBOS comment: nucl-ex/0506008
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
PHOBOS nucl-ex/0407012
v2
Npart
Transition is gradual, not abrupt…
62.4 GeV200 GeV
PHOBOS PRL 94, 082304
…vs. energy
Au+Au
Track-based 200 GeVHit-based 200 GeVHit-based 130 GeV
PHOBOS Nucl.Phys.A 757,28
AG
SSP
S
PHO
BO
S
…vs. centrality
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Extended longitudinal scaling…
PHOBOS PRL 94, 122303
PHOBOS nucl-ex/0409021
…in dN/dp+p, d+Au, Au+Au):
…in v2 (elliptic flow):
d+Au
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Universality of Nch
PHOBOS nucl-ex/0301017 & Nucl. Phys. A 757, 28
Npart scaling: Au+Au, d+Au
e+e-, p+p, A+A data
produces the same Nch
d+Aup+p
Au+Au
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Factorization of geometry and energy
Ratio of dN/d=0 at different energies:
Also differentially, at various pT values:
200/19.6 GeV
200/130 GeV
R(2
00/X
)
200/62.4 GeV
0.25<pT>= 1.25 2.50 3.38 3.88 GeV/c
<Npart>
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Our most recent results: dN/d in Au+Au at 62.4 GeV
PHOBOS
preliminary• most recent Au+Au run
• B field off
• 2 centrality methods:
scint. paddles at 3.2<<4.5
octagon ||<3
• 3 different dN/d methods:
analog, digital, ‘tracklets’
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
The most central data compared to other energies
PHOBOS
preliminary
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Our new 64.2 GeV point fits into the trend
• Mid-rapidity yields in
~6% most central events
• Logarithmic rise
A+Ap+p(p)
PHOBOSpreliminary
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Factorization of beam energy and collision geometry is also valid at 62.4 GeV
• at higher energies, hard collisions
should be more dominant
• Ncoll/Npart increases with centrality
• still, energy-independent
centrality evolution
Factorization of energy
and collision geometry
PHOBOS
preliminary
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Extended longitudinal scaling of charged hadrons(Also in d+Au and in v2)
PHOBOS
preliminary
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
RPC is precisely energy independentNpart
Ratio of 0-6% and 35-40% centrality bins, each normalized by Npart
90% C.L. syst. errors
PHOBOS
preliminary
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Total charged particle yields: Npart scaling
Error bands from the
extrapolation to high
PHOBOS
preliminary
• Integrated over the full range
• Nch is linearly increasing with Npart
• “wounded nucleon scaling”
• Scaled multiplicity is higher than in p+p
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Plans, PerspectivesData taking for PHOBOS has ended, but…
…lots of data on tape, still to be analyzed in the next years:
• Charged hadron spectra in Cu+Cu, p+Au, n+Au collisions
• Identified spectra and particle/antiparticle ratios (Cu+Cu, Au+Au)
• Particle production at very low pT (G. Stephans’ talk)
• Measurement of the Φ meson
• Multiplicity analysis using ‘tracklets’ and digital/analog method
• Event-by-event multiplicity fluctuations (Z. Chai’s talk)
• Two-particle correlations in d+Au collisions
• Elliptic and directed flow measurements
• Rare event searches
• etc… More news to come!
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Summary• Another great year for RHIC (& PHOBOS)
– “White Paper” reviews from the four experiments– Spectacular and diverse run with many different
collisions, and upgraded DAQ and computing• Luminosities even exceeding the goals
• Multiplicity measurement at 62.4 GeV– Fits into the known evolution with energy– Various scaling features observed/confirmed– Data are simpler than the models!
• Lot of data is still preliminary/in the works: – Much more results to come in the (near) future!
…see you in Budapest!
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
Gábor I. Veres AGS & RHIC Users Meeting, June 23, 2005AGS & RHIC Users Meeting, June 23, 2005
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