centrality dependence of charged hadron production at rhic d+au vs au+au gunther roland/mit for the...
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Centrality Dependence of Charged Hadron Production at RHIC
d+Au vs Au+Au
Gunther Roland/MITfor the
PHOBOS Collaboration
BNL June 18, 2003
Collaboration
Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Bruce Becker, Russell Betts,
Abigail Bickley, Richard Bindel, Andrzej Budzanowski, Wit Busza (Spokesperson), Alan Carroll,
Patrick Decowski, Edmundo Garcia, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen,
Stephen Gushue, Clive Halliwell, Joshua Hamblen, Adam Harrington, Conor Henderson,
David Hofman, Richard Hollis, Roman Holynski, Burt Holzman, Aneta Iordanova, Erik Johnson,
Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Jang Woo Lee, Willis Lin, Steven Manly,
Alice Mignerey, Gerrit van Nieuwenhuizen, Aaron Noell, Rachid Nouicer, Andrzej Olszewski,
Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Louis Remsberg, Christof Roland,
Gunther Roland, Joe Sagerer, Pradeep Sarin, Pawel Sawicki, Iouri Sedykh, Wojtek Skulski,
Chadd Smith, Peter Steinberg, George Stephans, Andrei Sukhanov, Ray Teng,
Marguerite Belt Tonjes, Adam Trzupek, Carla Vale, Robin Verdier, Gábor Veres, Bernard
Wadsworth, Frank Wolfs, Barbara Wosiek, Krzysztof Wozniak, Alan Wuosmaa, Bolek Wyslouch,
Jinlong Zhang
ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORYINSTITUTE OF NUCLEAR PHYSICS, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGYNATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGO
UNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER
PHOBOS preliminaryAu+Au 200 GeV15% central
How to connect observedfinal state particles to theory of strong interaction?
?
Rapidity Density600 1200Compilation by K. Eskola
Particle Multiplicity at RHIC
Particle Multiplicity at RHIC
Rapidity Density600 1200
PHOBOS Central Au+Au (200 GeV)
Compilation by K. Eskola
PHOBOS 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
• Multiplicity at low end of range– But: Energy density 30x nuclear matter
• Most models didn’t do so well
Parton Saturation
Low Energy
High Energy
Particle Multiplicity at RHIC
Rapidity Density600 1200
PHOBOS Central Au+Au (200 GeV)
Compilation by K. EskolaColor Glass
Rapidity Density600 1200
PHOBOS Central Au+Au (200 GeV)
Compilation by K. EskolaColor Glass
Hadron multiplicities at RHIC well
described by Parton Saturation
Particle Multiplicity at RHIC
Kharzeev & Levin, Phys. Lett. B523 (2001) 79
Data: PHOBOS,Phys. Rev. Lett. 87, 102303 (2001)
pT Spectra for Au+Au @ 200 GeV
0.2<y<1.4
Data: PHOBOS, nucl-ex/0302015Submitted to Phys Lett B
Relative to UA1 p+p
Centrality Dependence vs pT
PHOBOS, nucl-ex/0302015
Similar centrality dependence atpT = 0.5 and 4 GeV/c !
Initial StateCoherence?
Interaction in Dense Medium?
Predictions for d+Au
Vitev, nucl-th/0302002, Phys.Lett.B in press Vitev and M.Gyulassy, Phys.Rev.Lett. 89 (2002)
Central
Peripheral
Kharzeev, Levin, McLerran, hep-ph/021332
“~30%suppression of high pT particles”(central vs peripheral)
16% increase central vs peripheral
Nu
clea
r M
od
ific
atio
n F
acto
r R
dA
u
Parton Saturation pQCD
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)
Centrality Determination in d+Au
Multiplicity distributionPseudorapidity
Glauber Calculation•Hijing 1.383
•Hulthen w.f.•41mb inelastic cross-section
•Full GEANT Simulation
HIJING Simulation
dN
/d
Co
un
ts
d+Au pT Spectra
Compare to p+p reference…
From Glauber(HIJING 1.383)
41mb (same as for Glauber)
From UA1, usingPythia to go from|| < 2.5 to 0.2 < < 1.4
…for each centrality bin
PHOBOS d+Au: nucl-ex/0306025
central Au+Au
All syst. uncertainties: 90% C.L.
PHOBOS d+Au: nucl-ex/0306025
RdAu vs pT
Centrality dependence of RdAu
Data disfavor initial state interpretation of Au+Au high-pT suppression
N.B. Smaller ppinel would increase
RdAu central vs RdAu peripheral
PHOBOS d+Au: nucl-ex/0306025
All syst. uncertainties: 90% C.L.
Initial State ‘Final State’ Interactions
Multiplicity systematicsconnected to initial state
Consistent with parton saturation picture
Interaction of fast partonswith dense medium has been observed
Quantitative diagnostic tool now established
Connection to QCD
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