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Charged Hadron p T Spectra from Au+Au at s NN = 62.4 GeV. C o nor Henderson, MIT For the collaboration Division of Nuclear Physics, Chicago 29 October 2004. Collaboration (October 2004).
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Charged Hadron pT Spectra from Au+Au at sNN = 62.4 GeV Conor Henderson, MIT For the collaboration Division of Nuclear Physics, Chicago 29 October 2004
Collaboration (October 2004) Burak Alver, Birger Back,Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Abigail Bickley, Richard Bindel, Wit Busza (Spokesperson), Alan Carroll, Zhengwei Chai, Vasundhara Chetluru, Patrick Decowski, Edmundo García, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Clive Halliwell, Joshua Hamblen, Ian Harnarine, Conor Henderson, David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta Iordanova, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Wei Li, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Heinz Pernegger, Corey Reed, Christof Roland, Gunther Roland, Joe Sagerer, 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
PHOBOS Detector 2004 T0 counter 137000 Silicon Pad Channels Paddle Trigger Counter Spectrometer NIM A 499, 603-623 (2003)
Charged Hadron pT Spectra • Corrected for: • Acceptance • Efficiency • Feed-down • Secondaries • Momentum resolution • Ghosts • Bin width • Dead channels nucl-ex/0405003
RAA for Au+Au at sNN = 62.4 GeV • RAA significantly higher at 62.4 GeV than at 200 GeV
RAA at 62.4 GeV from Theory (I) • From parton energy loss calculations: Adil, Gyulassy: nucl-th/0405036 Vitev: nucl-th/0404052 XN Wang: nucl-th/0405029
RAA at 62.4 GeV from Theory (II) Eskola, Honkanen, Salgado, Wiedemann: hep-ph/0406319 Gallmeister, Cassing: hep-ph/0408223
Factorization of Energy and Centrality Dependence • Centrality dependence of • vs. pT is the same at both energies • Challenge to collision models to reproduce this
Factorization for Particle Multiplicity PHOBOS, Phys. Rev. C70, 021902(R) (2004) • Factorization also seen for mid-rapidity multiplicity, from 19.6 to 200 GeV
PHOBOS PID Capabilities at 62.4 GeV dE/dx in Silicon Time-of-flight
Conclusions • PHOBOS has measured h pT spectra up to 4 GeV in Au+Au collisions at sNN = 62.4 GeV • RAA significantly higher at 62.4 GeV than at 200 GeV • But the centrality dependence of the pT yields found to be remarkably similar at the two energies - this factorization also seen in mid-rapidity particle yields from 19.6 to 200 GeV • Appears to be a key feature of heavy-ion collisions which remains to be understood
The PHOBOS Spectrometer 10cm 70 cm z y • Silicon sensors • Outer layers in 2T magnetic field • High segmentation in bending direction • Tracking within 10 cm of interaction point • Coverage near mid-rapidity x
Npart and Ncoll vs. sNN • Nucleon-nucleon inelastic cross-section grows with collision energy • So Ncoll/Npart increases with sNN
p+p Reference Spectrum at 62.4 & 200 GeV SFM @ISR Z Phys. C 69, 55 (1995) Nucl. Phys. B 207, 1 (1982) Phys. Lett. B 83, 257 (1979) Nucl. Phys. B 335, 261 (1990)
PHOBOS and STAR at 200 GeV PLB 578297, 2004 PRL 91, 172302, 2003
PHENIX pT Spectra at sNN = 200 GeV Insert PHENIX reference
RAA at 62.4 GeV from Theory (IV) Adil, Gyulassy: nucl-th/0405036
RAA at 62.4 GeV from Theory (II) • pQCD collinearly factorized formalism with radiative parton energy loss Eskola, Honkanen, Salgado, Wiedemann: hep-ph/0406319
RAA at 62.4 GeV from Theory (III) Gallmeister, Cassing: hep-ph/0408223 • Hadron string dynamical transport model • Hadron attenuation attributed to inelastic collisions of leading pre-hadron with dense hadronic medium