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Charged Hadron p T Spectra from Au+Au at  s NN = 62.4 GeV

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 p T Spectra from Au+Au at  s NN = 62.4 GeV

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  1. 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

  2. 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

  3. PHOBOS Detector 2004 T0 counter 137000 Silicon Pad Channels Paddle Trigger Counter Spectrometer NIM A 499, 603-623 (2003)

  4. Centrality Range Studied at 62.4 GeV

  5. Charged Hadron pT Spectra • Corrected for: • Acceptance • Efficiency • Feed-down • Secondaries • Momentum resolution • Ghosts • Bin width • Dead channels nucl-ex/0405003

  6. RAA for Au+Au at sNN = 62.4 GeV • RAA significantly higher at 62.4 GeV than at 200 GeV

  7. 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

  8. RAA at 62.4 GeV from Theory (II) Eskola, Honkanen, Salgado, Wiedemann: hep-ph/0406319 Gallmeister, Cassing: hep-ph/0408223

  9. Factorization of Energy and Centrality Dependence • Centrality dependence of • vs. pT is the same at both energies • Challenge to collision models to reproduce this

  10. Factorization for Particle Multiplicity PHOBOS, Phys. Rev. C70, 021902(R) (2004) • Factorization also seen for mid-rapidity multiplicity, from 19.6 to 200 GeV

  11. PHOBOS PID Capabilities at 62.4 GeV dE/dx in Silicon Time-of-flight

  12. 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

  13. Back-up Slides

  14. 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

  15. Definitions

  16. Centrality Range at 200 GeV

  17. Centrality Range at 62.4 & 200 GeV

  18. Npart and Ncoll vs. sNN • Nucleon-nucleon inelastic cross-section grows with collision energy • So Ncoll/Npart increases with sNN

  19. RAANpart and RPCNpart

  20. RPCNpart vs. Npart in pT bins for 200GeV

  21. 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)

  22. PHOBOS and STAR at 200 GeV PLB 578297, 2004 PRL 91, 172302, 2003

  23. PHENIX pT Spectra at sNN = 200 GeV Insert PHENIX reference

  24. RAA at 62.4 GeV from Theory (IV) Adil, Gyulassy: nucl-th/0405036

  25. RAA at 62.4 GeV from Theory (II) • pQCD collinearly factorized formalism with radiative parton energy loss Eskola, Honkanen, Salgado, Wiedemann: hep-ph/0406319

  26. 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

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