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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). - PowerPoint PPT Presentation
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Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
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
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 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 LABORATORYINSTITUTE OF NUCLEAR PHYSICS PAN, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGY
NATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGOUNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004Spectrometer
Paddle Trigger Counter
137000 Silicon Pad ChannelsT0 counter
PHOBOS Detector 2004
NIM A 499, 603-623 (2003)
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Centrality Range Studied at 62.4 GeV
Centrality <Npart> <Ncoll>
45-50% 61 7 85 14
35-45% 86 9 136 22
25-35% 130 10 240 30
15-25% 189 9 402 36
6-15% 266 9 643 48
0-6% 335 11 883 65
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Charged Hadron pT SpectraCorrected for:
• Acceptance
• Efficiency
• Feed-down
• Secondaries
• Momentum resolution
• Ghosts
• Bin width
• Dead channelsnucl-ex/0405003
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
RAA for Au+Au at sNN = 62.4 GeV
• RAA significantly higher at 62.4 GeV than at 200 GeV
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
RAA at 62.4 GeV from Theory (I)
Vitev:
nucl-th/0404052
XN Wang:
nucl-th/0405029
Adil, Gyulassy:
nucl-th/0405036
• From parton energy loss calculations:
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
RAA at 62.4 GeV from Theory (II)
Eskola, Honkanen, Salgado,
Wiedemann: hep-ph/0406319
Gallmeister, Cassing: hep-ph/0408223
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Factorization of Energy and Centrality Dependence
• Centrality dependence of
vs. pT is the same at both energies
• Challenge to collision models to reproduce this
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Factorization for Particle MultiplicityPHOBOS, Phys. Rev. C70, 021902(R) (2004)
• Factorization also seen for mid-rapidity multiplicity, from 19.6 to 200 GeV
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
PHOBOS PID Capabilities at 62.4 GeV
dE/dx in Silicon Time-of-flight
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
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
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Back-up Slides
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
The PHOBOS Spectrometer
z
y
70 cm 10cm
x
• Silicon sensors• Outer layers in 2T
magnetic field• High segmentation in
bending direction • Tracking within 10 cm
of interaction point
• Coverage near mid-rapidity
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Definitions
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Centrality Range at 200 GeV
Centrality <Npart> <Ncoll>
45-50% 65 4 99 11
35-45% 93 5 164 15
25-35% 138 6 286 25
15-25% 200 8 483 40
6-15% 276 9 762 57
0-6% 344 11 1040 77
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Centrality Range at 62.4 & 200 GeV
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Npart and Ncoll vs. sNN
• Nucleon-nucleon inelastic cross-section grows with collision energy
• So Ncoll/Npart increases with sNN
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
RAANpart and RPC
Npart
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
RPCNpart vs. Npart in pT bins for 200GeV
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
Z Phys. C 69, 55 (1995)
Nucl. Phys. B 207, 1 (1982)
Phys. Lett. B 83, 257 (1979)
Nucl. Phys. B 335, 261 (1990)
p+p Reference Spectrum at 62.4 & 200 GeV
SFM @ISR
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
PHOBOS and STAR at 200 GeV
PLB 578297, 2004
PRL 91, 172302, 2003
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
PHENIX pT Spectra at sNN = 200 GeV
Insert PHENIX reference
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
RAA at 62.4 GeV from Theory (IV)
Adil, Gyulassy: nucl-th/0405036
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
RAA at 62.4 GeV from Theory (II)
Eskola, Honkanen, Salgado, Wiedemann: hep-ph/0406319
• pQCD collinearly factorized formalism with radiative parton energy loss
Conor Henderson, MITDivision of Nuclear Physics, Chicago, 2004
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