1、Centrality Dependence of Charged Hadron Production at RHIC d+Au vs Au+Au,Gunther Roland/MIT for 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
2、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 K
3、ane, 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
4、 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, Gbor Veres, Bernard Wadsworth, Frank Wolfs, Barbara Wosiek, Krzysztof Wozniak, Alan Wuosmaa, Bolek Wyslouch,
5、 Jinlong Zhang ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORYINSTITUTE OF NUCLEAR PHYSICS, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGYNATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGOUNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER,How to connect observed final state p
6、articles to theory of strong interaction?,?,Rapidity Density,600,1200,Compilation by K. Eskola,Particle Multiplicity at RHIC,Particle Multiplicity at RHIC,PHOBOS multiplicity papers:Phys. Rev. Lett. 85 , 3100 (2000) Phys. Rev. Lett. 87, 102303 (2001) Phys. Rev. C 65 , 31901R (2002) Phys.Rev. Lett. 8
7、8 , 22302 (2002) Phys. Rev. C 65 , 061901R (2002) nucl-ex/0210015, PRL in Press nucl-ex/0301017, subm. to PRL,Multiplicity at low end of range But: Energy density 30x nuclear matter Most models didnt do so well,Parton Saturation,Low Energy,High Energy,Particle Multiplicity at RHIC,Color Glass,Color
8、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,Centrality Dependence vs pT,PHOBOS, nucl-ex/0302015,Similar centrality depe
9、ndence at pT = 0.5 and 4 GeV/c !,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 peripher
10、al,Nuclear Modification Factor RdAu,Parton Saturation,pQCD,PHOBOS Detector 2003,SPECTRIG,mini-pCal,pCal,Moved TOF walls back 5 m from interaction point New on-line high pT Spectrometer Trigger New “time-zero” (T0) Cerenkov detectors On-line vertexing and ToF start time Forward proton calorimeters on
11、 Gold and Deuteron sides DAQ upgrade (x10),Centrality Determination in d+Au,Multiplicity distribution,Pseudorapidity,Glauber Calculation Hijing 1.383 Hulthen w.f. 41mb inelastic cross-section Full GEANT Simulation,HIJING Simulation,dN/dh,Counts,d+Au pT Spectra,PHOBOS d+Au: nucl-ex/0306025,central Au
12、+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 sppinel 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 systematics connected to initial stateConsistent with parton saturation picture,Interaction of fast partons with dense medium has been observedQuantitative diagnostic tool now established,Connection to QCD,
