Gunther Roland - MITPHOBOS QM2005 Structure and Fine Structure of Hadron Production at RHIC Gunther Roland Massachusetts Institute of Technology New Results.

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Gunther Roland - MITPHOBOS QM2005 Structure and Fine Structure of Hadron Production at RHIC Gunther Roland Massachusetts Institute of Technology New Results from the PHOBOS Collaboration

Gunther Roland - MITPHOBOS QM20052 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, Constantin Loizides, 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 LABORATORYBROOKHAVEN NATIONAL LABORATORY INSTITUTE OF NUCLEAR PHYSICS PAN, KRAKOWMASSACHUSETTS INSTITUTE OF TECHNOLOGY NATIONAL CENTRAL UNIVERSITY, TAIWANUNIVERSITY OF ILLINOIS AT CHICAGO UNIVERSITY OF MARYLANDUNIVERSITY OF ROCHESTER PHOBOS Collaboration Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM20053 Phobos Experiment Control ParametersDataScaling Laws PHOBOS Experiment - Commissioning Run Low p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM20054 PHOBOS Experiment - Run 1 Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM2005 PHOBOS Experiment - Run 2 Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM20056 Phobos Experiment Control ParametersDataScaling Laws PHOBOS Experiment - Run 3 Low p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM20057 Phobos Experiment Control ParametersDataScaling Laws PHOBOS Experiment - Run 4 Low p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM20058 Phobos Experiment Control ParametersDataScaling Laws PHOBOS Experiment - Run 5 Low p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM20059 Phobos Experiment Control ParametersDataScaling Laws PHOBOS Experiment - Run 6 Low p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM = shown in this talk p+pd+AuCu+CuAu+Au ~1 GeV system [in millions] Phobos Experiment Control ParametersDataScaling Laws Number of Events to Tape Low p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM Internet Master Slave User PROOF CatWeb – data management (650k files, 400 TByte) Easy www interface to stage HPSS  RCF 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 Transparent, 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! Phobos Experiment Control ParametersDataScaling Laws PHOBOS Computing Architecture See poster by Maarten Ballintijn Low p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Mission Statement Systematic study of charged hadron production Search for –Organizing principles (Scaling laws, Sum rules) Common features with elementary systems Collective effects Low p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Collision Energy Drees, QM ‘01 Energy DensityBalance of ‘Hard’ vs ‘Soft’ Particle Production Low p T SummaryFluctuations Central A+A

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Collision Geometry L~A 1/3 N coll = # of NN collisions: ~A 4/3 N part /2 ~ A “Participants” “Collisions” PHOBOS Glauber MC Low p T SummaryFluctuations Au+Au Cu+Cu Au+Au Cu+Cu

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Transverse Geometry PHOBOS Glauber MC Au+Au vs Cu+Cu –Interplay of initial geometry and initial density –Test ideas of early thermalization and collectivity wrt reaction plane Low p T SummaryFluctuations x y Nucleus 2 Nucleus 1 Participant Region Au+Au Cu+Cu

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws PHOBOS Data Low p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Charged Hadron dN/d  Low p T SummaryFluctuations centrality Au+Au : PRL 91, (2003) d+Au : PRL 93, (2004) 19.6 GeV62.4 GeV130 GeV 200 GeV preliminary Cu+Cu d+Au Au+Au PHOBOS

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Charged Hadron p T Spectra Low p T SummaryFluctuations Au+Au: PRL 94, (2005), PLB 578, 297 (2004) d+Au: Phys. Rev. Lett. 91, (2003) preliminary 62.4 GeV 200 GeV Cu+Cu d+Au Au+Au PHOBOS centrality

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Directed Flow Low p T SummaryFluctuations Au+Au 19.6 GeV62.4 GeV130 GeV 200 GeV preliminary PHOBOS See poster by Alice Mignerey

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Elliptic Flow Low p T SummaryFluctuations Au+Au 19.6 GeV62.4 GeV130 GeV 200 GeV preliminary PHOBOS Cu+Cu Au+Au: PRL (2005)

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Yields in Cu+Cu vs Au+Au Low p T SummaryFluctuations Q: How does charged hadron production in Cu+Cu compare to Au+Au?

Gunther Roland - MITPHOBOS QM dN/d  in Cu+Cu vs Au+Au Unscaled dN/d  very similar for Au+Au and Cu+Cu at same N part Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations Cu+Cu Preliminary 3-6%, N part = 100 PHOBOS 62.4 GeV200 GeV Au+Au Preliminary 35-40%,N part = 98 Cu+Cu Preliminary 3-6%, N part = 96 Au+Au 35-40%, N part = 99 See poster by Richard Hollis

Gunther Roland - MITPHOBOS QM dN/d  in Cu+Cu vs Au+Au Unscaled dN/d  very similar for Au+Au and Cu+Cu at same N part Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations Cu+Cu Preliminary 15-25%, N part = 61 PHOBOS 62.4 GeV200 GeV Au+Au Preliminary 45-50%,N part = 62 Cu+Cu Preliminary 15-25%, N part = 60 Au+Au 45-55%, N part = 56 Also true for mid-central Cu+Cu vs peripheral Au+Au

Gunther Roland - MITPHOBOS QM Anti-proton/proton ratio Phobos Experiment Control ParametersDataScaling Laws p/p ratio very similar in Cu+Cu and Au+Au Low p T SummaryFluctuations See poster by Vasu Chetluru

Gunther Roland - MITPHOBOS QM Particle Production vs p T Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations Charged hadron R AA 200 GeV 63 GeV Au+Au: PRL 94, (2005), PLB 578, 297 (2004) Cu+Cu preliminary Au+Au Cu+Cu preliminary

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Yields vs N part, 200 GeV Low p T SummaryFluctuations Au+Au: PRL 94, (2005), PLB 578, 297 (2004) See poster by Gerrit van Nieuwenhuizen Au+Au

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Yields vs N part, 200 GeV Low p T SummaryFluctuations Au+Au: PRL 94, (2005), PLB 578, 297 (2004) See poster by Gerrit van Nieuwenhuizen Cu+Cu preliminary Au+Au

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Yields vs N part, 62 GeV Low p T SummaryFluctuations Au+Au: PRL 94, (2005) Au+Au

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Yields vs N part, 62 GeV Low p T SummaryFluctuations Au+Au: PRL 94, (2005) Cu+Cu preliminary Au+Au

Gunther Roland - MITPHOBOS QM A: For same system size (N part, N coll ), Cu+Cu and Au+Au are very similar: –Total multiplicity –Mid-rapidity dN/d  –p/p –dN/d  vs  –dN/dp T (R AA ) Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations Q: How does charged hadron production in Cu+Cu compare to Au+Au? Yields in Cu+Cu vs Au+Au

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Geometry and Energy Low p T SummaryFluctuations Q: What is the interplay between collision centrality (geometry) and collision energy? Balance of hard/soft processes

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Energy/Centrality Factorization Low p T SummaryFluctuations Au+Au: Phys. Rev. C70, (R) (2004) + prel GeV PHOBOS Au+Au

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Energy/Centrality Factorization Low p T SummaryFluctuations 200/ / /130 Cu+Cu preliminary Au+Au PHOBOS HIJING Saturation Factorization of energy and centrality dependence Initial state effect? Ratio of dN/d  =0 relative to 200 GeV vs centrality Au+Au: Phys. Rev. C70, (R) (2004) + prel GeV Au+Au PHOBOS Cu+Cu preliminary x-section uncertainty c.f. Armesto, Salgado, Wiedemann hep-ph/

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Energy/centrality factorization up to p T ≈ 4 GeV/c for N part > 40 Low p T SummaryFluctuations Factorization in p T, I Au+Au Cu+Cu preliminary Ratio of charged hadron yields in 200 GeV to 62 GeV Au+Au: PRL 94, (2005) = 0.25 GeV/c = 1.25 GeV/c = 2.5 GeV/c = 3.38 GeV/c = 3.88 GeV/c

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Same shape evolution from central to peripheral at 200 GeV and 62 GeV Low p T SummaryFluctuations Factorization in p T, II Au+Au Normalized for central events Au+Au: PRL 94, (2005) Cu+Cu preliminary

Gunther Roland - MITPHOBOS QM Limiting Fragmentation (Au+Au) Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations 19.6 GeV62.4 GeV130 GeV200 GeV PHOBOS preliminary “Extended Longitudinal Scaling” of all longitudinal distributions  - y beam preliminary PHOBOS Au+Au 0-6% Au+Au 0-40% Au+Au 0-40% 200GeV 130GeV 62.4 GeV (prel) 19.6 GeV

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Limiting Fragmentation (Cu+Cu) Low p T SummaryFluctuations preliminary PHOBOS 62.4 GeV200 GeV ‘Extended Longitudinal Scaling’ also seen in Cu+Cu Persists from p+p to Au+Au over large range in  ’ preliminary PHOBOS  - y beam Cu+Cu 0-6% 200GeV 62.4GeV Cu+Cu 0-40%

Gunther Roland - MITPHOBOS QM R PC is energy independent N part Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations Ratio of 0-6% and 35-40% centrality bins, each normalized by N part PHOBOS preliminary Au+Au 35-40% 0-6% Au+Au 0-6% Au+Au 35-40% 200GeV 130GeV 62.4 GeV (prel) 19.6 GeV 200GeV 130GeV 62.4 GeV (prel) 19.6 GeV

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Geometry and Energy Low p T SummaryFluctuations Q: What is the interplay between collision centrality (geometry) and collision energy? Balance of hard/soft processes A: Factorization of geometry and energy dependence is observed: –N part scaling –dN/d  =0 –Limiting fragmentation –p T spectra Rules out N part /N coll two-component picture Dominance of geometry?

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Elliptic Flow, Geometry & Density Low p T SummaryFluctuations Q: How does elliptic flow scale with geometry and density?

Gunther Roland - MITPHOBOS QM Elliptic Flow in Cu+Cu vs Au+Au Phobos Experiment Control ParametersDataScaling Laws Sizable v 2 for Cu+Cu Much larger than transport-model predictions Low p T SummaryFluctuations preliminary PHOBOS 200 GeV h ± Statistical errors only Cu+Cu preliminary PHOBOS 200 GeV Statistical errors only Au+Au 0-40% centrality See talk by Steve Manly

Gunther Roland - MITPHOBOS QM preliminary PHOBOS 200 GeV h ± Statistical errors only Cu+Cu preliminary Au+Au PHOBOS 200 GeV Statistical errors only Elliptic Flow vs N part Phobos Experiment Control ParametersDataScaling Laws Substantial v 2 even for most central bin in Cu+Cu Low p T SummaryFluctuations v 2 near mid-rapidity

Gunther Roland - MITPHOBOS QM Eccentricity Calculation Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations Standard Eccentricity x y Nucleus 2 Nucleus 1 Participant Region b Au+Au Cu+Cu Au+Au Nucleus 1 Nucleus 2 Participant Region x y Participant Eccentricity b Au+Au Cu+Cu Au+Au

Gunther Roland - MITPHOBOS QM Elliptic Flow vs N part, II Standard Eccentricity Cu+Cu preliminary Au+Au PHOBOS 200 GeV “Participant Eccentricity” allows v 2 scaling from Cu+Cu to Au+Au Participant Eccentricity PHOBOS 200 GeV Au+Au Cu+Cu preliminary Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM Standard Eccentricity Cu+Cu Au+Au Participant Eccentricity Cu+Cu Au+Au Low Density Limit: STAR, PRC (2002) Voloshin, Poskanzer, PLB (2000) Heiselberg, Levy, PRC , (1999) Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Elliptic Flow, Geometry & Density Low p T SummaryFluctuations Q: How does elliptic flow scale with geometry and density? A: Large elliptic flow observed in Cu+Cu –Non-vanishing for central events –“Non-flow” effects? –Expansion driven by participant eccentricity?

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations Q: What Physics Lessons have we learned? A1: Energy/Centrality factorization implies suppression/saturation of initial particle production If this persists at LHC, underlying physics will dominate HIC at LHC Physics Lessons, I

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations Q: What Physics Lessons have we learned? A2: Strong collective flow observed in Cu+Cu emphasizes the need for understanding of early thermalization/pressure build up Au+Au Cu+Cu Physics Lessons, II

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Continuing Physics Program Low p T SummaryFluctuations Q: What is the current and future physics program for PHOBOS?

Gunther Roland - MITPHOBOS QM Multiplicity Fluctuations Phobos Experiment Control ParametersDataScaling LawsLow p T SummaryFluctuations Correlated particle emission in ‘clusters’ Extract cluster size from forward/backward multiplicity correlations See talk by Peter Steinberg Au+Au 200 GeV 0-20%central PHOBOS preliminary Effective cluster size

Gunther Roland - MITPHOBOS QM Search for Rare Events Phobos Experiment Control ParametersDataScaling Laws Search for ‘unusual’ events Understand tails (≈10 -4 ) in terms of known backgrounds See talk by George Stephans Low p T SummaryFluctuations PHOBOS preliminary Au+Au 3% central 2M Events 200 Events

Gunther Roland - MITPHOBOS QM Particle Production at Low p T Phobos Experiment Control ParametersDataScaling Laws See talk by Adam Trzupek (spectra) and poster by Siarhei Vaurynovich(Phi) Low p T SummaryFluctuations 200 GeV d+Au (min bias) 62.4 GeV Au+Au (15% central) Unique measurements at low p T Blastwave fit

Gunther Roland - MITPHOBOS QM Phobos Experiment Control ParametersDataScaling Laws Continuing Physics Program Low p T SummaryFluctuations Q: What is the current and future physics program for PHOBOS? A: We still have a long way to go –Complete systematics of hadron production and anisotropic flow –Comprehensive studies of correlations over full acceptance –Comprehensive study of charged hadron and  production at very low p T Make full use of the large Au+Au and Cu+Cu datasets

Gunther Roland - MITPHOBOS QM Adam Trzupek “Particle production at very low and intermediate transverse momenta in Au+Au and d+Au collisions” (Fri, 15:00 Rm #0.83) Steve Manly “System-size and energy dependence of elliptic flow” (Fri, 16:20, Rm #0.81) Peter Steinberg “Charged hadron multiplicity fluctuations in Au+Au collisions at RHIC” (Sat, 17:00, Globe Hall) George Stephans “Two-particle angular correlations in d+Au collisions” (Mon, 16:00, Globe Hall) PHOBOS Talks Alice Mignerey “Systematic study of directed flow at RHIC” Gerrit van Nieuwenhuizen “Charged Hadron spectra in Cu+Cu and Au+Au collisions at RHIC” Richard Hollis “Charged particle multiplicities from Cu+Cu, Au+Au and d+Au collisions at RHIC” Vasundhara Chetluru “Particle ratios in Cu+Cu collisions at RHIC Siarhei Vaurynovich “Measurement of phi mesons with the PHOBOS detector” Maarten Ballintijn “The PHOBOS interactive computing architecture at RHIC” PHOBOS Posters