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Open Charm Production in pp and dAu Collisions at Large Rapidity

Open Charm Production in pp and dAu Collisions at Large Rapidity. Ming Xiong Liu Los Alamos National Lab (for the PHENIX Collaboration). Open Charm @ y~0. Scales with number of nucleon binary collisions in d+Au & Au+Au @ y ~0. Open Charm at Large Rapidity. Gluon saturation/CGC

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Open Charm Production in pp and dAu Collisions at Large Rapidity

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  1. Open Charm Production in pp and dAu Collisions at Large Rapidity Ming Xiong Liu Los Alamos National Lab (for the PHENIX Collaboration)

  2. Open Charm @ y~0 • Scales with number of nucleon binary collisions in d+Au & Au+Au @ y ~0

  3. Open Charm at Large Rapidity • Gluon saturation/CGC • PHENIX forward muons dAu D. Kharzeev & K. Tuchin hep-ph/0310358 AuAu

  4. 2 3 1 0 PT Final State Scatterings J. Qiu & I. Vitev, 10/2004 • Coherent multiple scattering and XB rescaling • Heavy quark mass effects

  5. The Experimental Goal • Probe nuclear medium effects: • Initial state gluon saturation • Final state nuclear scatterings RdAu at large rapidity: • light hadrons • Heavy hadrons • Provide baseline reference for QGP signatures in AuAu collisions • Thermal production • QGP medium effects • Baseline reference for J/Psi etc (see WooJin’s Talk)

  6. Run I, 2001 Au-Au beams at s=130 GeV • Open charm from PHENIX • Run II, 2002 Au-Au beams and p-p at s=200 GeV • Open charm and J/Y from PHENIX • Run III, 2003 d-Au, p-p at s=200 GeV • Open charm from PHENIX and STAR, J/Y from PHENIX • Run IV, 2004 Au-Au, s=200 GeV, p-p at s=200 GeV • More measurements to come

  7. The PHENIX detector gold deuteron North Muon arm : 2.4 > h > 1.2 South Muon arm : -1.2 > h > -2.0

  8. Major sources of “muon” tracks Tracker Absorber Identifier Muon 2 Collision 3 1 Hadron 4 5 Collision range Absorber 1 : Hadrons, interacting and absorbed (98%) 2 : Charged/K's,"decaying" before absorber (≤1%) 3 : Hadrons, penetrating and interacting ("stopped") 4 : Hadrons, "punch-through" 5 : Prompt muons, desired signal Items 2 and 4 are small fraction of the original hadrons, but are more than prompt muon signal 5.

  9. m p Normalized Event Z Vertex Distribution • Filter out decay muon by Z-vertex analysis • Muon yield increasing linearly as function of distance from the absorber, indicates p/K decay muon is detected. • Linear shape of z-vertex slopeis becausectg~100 [m]. • p/K decaymdominates single muons. • Promptmor punch through background has no vertex dependent. z [cm] MuTr Absorber Beam Beam BBC Cu Fe

  10. Raw Muon Distributions • Decay muons • Prompt muons 1.5 < Pt < 2.0 2.0 < Pt < 2.5 MC Muon Pt Event VTX

  11. Prompt muon and punch-through hadron separation - work in progress number of tracks 2 3 4 Prompt muon Hadron Gap2 Gap3 Gap4

  12. Muon peak Hadronic tail Measurement of Stopped Hadrons Stopping power: Use shallow MuID absorber layers to select stopped hadrons for Ptot > 1.9GeV: muon contamination < 3%

  13. Summary and Outlook • The goal: RdAu with open charm at large forward/backward rapidities • Probing nuclear medium effects • gluon saturation • nuclear scattering at large rapidity • Technical challenges • Muons from charm decays • Prompt muons • Background tracks • muons from light meson decays (see Xiaorong Wang’s talk) • punch-through hadrons- work in progress • Expect results in near future

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