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Multiplicity Fluctuations in 200 GeV Au-Au Collisions

Multiplicity Fluctuations in 200 GeV Au-Au Collisions. Zhengwei Chai Brookhaven National Laboratory for the Collaboration APS April Meeting, Denver, 2004. Collaboration.

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Multiplicity Fluctuations in 200 GeV Au-Au Collisions

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  1. Multiplicity Fluctuations in 200 GeV Au-Au Collisions Zhengwei Chai Brookhaven National Laboratory for the Collaboration APS April Meeting, Denver, 2004

  2. Collaboration Birger Back,Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Abigail Bickley, Richard Bindel, Wit Busza (Spokesperson), Alan Carroll, Zhengwei Chai, Patrick Decowski, Edmundo García, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Clive Halliwell, Joshua Hamblen, Adam Harrington, Michael Hauer, Conor Henderson, David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta Iordanova, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Christof Roland, Gunther Roland, Joe Sagerer, Helen Seals, Iouri Sedykh, Wojtek Skulski, Chadd Smith, Maciej Stankiewicz, Peter Steinberg, George Stephans, Andrei Sukhanov, Marguerite Belt Tonjes, Adam Trzupek, Carla Vale, Sergei Vaurynovich, Robin Verdier, Gábor Veres, Peter Walters, Edward Wenger, Frank Wolfs, Barbara Wosiek, Krzysztof Woźniak, Alan Wuosmaa, Bolek Wysłouch ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORY INSTITUTE OF NUCLEAR PHYSICS PAN, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGY NATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGO UNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER Zhengwei Chai

  3. Fluctuations in Particle Production • Particle production in Au-Au collisions is dominated by overlapping geometry of the colliding ions, thus the particle multiplicity mainly depends on the number of participants Npart. • Dynamical fluctuations other thanstatistical and Npart fluctuations may provide insights on the intrinsic mechanisms of the particle production. • Event-by-event multiplicity fluctuation could be a useful signature of the QGP-Hadron Gas phase transition due to the large difference of the degree of freedom between the two phases. • Dynamical fluctuations are also related to particle correlations, such as jets, resonances and clusters. Zhengwei Chai

  4. N1+N2 N1- N2 Event-by-event fluctuation observable s(C) • Study multiplicity fluctuation using • s(C) = RMS of C distribution • Npartfluctuations suppressed in s(C) • s(C) = 1 for pure statistical fluctuations • s(C)≠1 indicates additional fluctuations Zhengwei Chai

  5. PHOBOS Detectors Cerenkov Trigger Counters Time of Flight Counters Octagon Multiplicity Detector and Vertex Detector (Silicon) Ring Multiplicity Detectors (Silicon) Beryllium Beam Pipe Spectrometer Detectors (Silicon) Paddle Trigger Counters Octagon Zhengwei Chai

  6. PHOBOS Capability in Charged Particle Multiplicity Analysis PHOBOS Multiplicity Detectors Acceptance Coverage 0 ≤ f ≤ 2p Zhengwei Chai

  7. Constructing Multiplicity in Au-Au Collisions • Octagon silicon sensors provide • Number of hits (Nhit) • Sum of the angle-corrected dE • for charged particles (E) • Nhit=Nmax(1-exp(-E/Emax)) • Emax/Nmax: average dE by a charged particle in selected h bin • Occupancy-corrected multiplicity • N = E /(Emax/Nmax) Number of hits (Nhit) Energy (E) • Multiplicities N1, N2 in forward and backward equal size h bins • N1, N2 s(C) Zhengwei Chai

  8. Preliminary Fluctuation Analysis Result • Data s(C) agrees with • Rec.Hijing+Geants(C) • Data and Rec. MCs(C) • dominated by detector • responses • Estimated systematic • error 5% (not shown) Phobos Prelim. Data Rec. Hijing+Geant Hijing (half f) s(C) Zhengwei Chai

  9. Preliminary Fluctuation Analysis Result s(C) • Data and Rec. MCs(C) • agree very well • Hijings(C) increases • with the separation in • pseudo-rapidity space • Estimated systematic • error 5%(not shown) h Zhengwei Chai

  10. Fluctuation Sources in Rec. MC Multiplicity • Acceptance Effects • Secondaries • dE/dx Fluctuations • Landau fluctuation • Velocity (b) variation • Hijing non-statistical • fluctuations (physics) s(C) h Zhengwei Chai

  11. Preliminary Fluctuation Analysis Result s(C) • Data and Rec. MCs(C) • increase with the h bin • size • Hijings(C) increases • with the h bin size • Estimated systematic • error 5%(not shown) Dh Zhengwei Chai

  12. Summary and Outlook • Analyzed multiplicity fluctuation of the charged particle production • in Au-Au collisions at =200GeV over wide pseudo-rapidity • range (-3.0<h<+3.0) • The measured fluctuations in the Data are consistent with that in • reconstructed Au-Au MC (Hijing + Geant) • Current new dynamic fluctuation search is complicated by dominant • detector responses • The physics fluctuations grow with increasing bin separation (h) and • width (Dh) and may be explained by jets or particle production in • clusters • Further studies are being extended to the full acceptance(-5.4<h<+5.4) • for a variety of beam energies Zhengwei Chai

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