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RHIC-STAR 实验

RHIC-STAR 实验. 徐庆华， 邓建 2011.11.25. RHIC-STAR 实验情况 STAR 上超子极化转移的测量 STAR forward upgrade plan & eRHIC (EIC). PHOBOS. BRAHMS. RHIC. PHENIX. STAR. AGS. TANDEMS. Relativistic Heavy Ion Collider (RHIC) at Brookhaven -- also the first polarized pp collider. What does RHIC do?.

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RHIC-STAR 实验

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  1. RHIC-STAR实验 徐庆华，邓建 2011.11.25 • RHIC-STAR实验情况 • STAR上超子极化转移的测量 • STAR forward upgrade plan & eRHIC (EIC)

  2. PHOBOS BRAHMS RHIC PHENIX STAR AGS TANDEMS Relativistic Heavy Ion Collider (RHIC) at Brookhaven -- also the first polarized pp collider

  3. What does RHIC do? 1) At 200 GeV top energy - Study medium properties, EoS - pQCD in hot and dense medium 2) RHIC beam energy scan - Search for the QCD critical point - Chiral symmetry restoration Polarized spin program @ 200, 500 GeV - Study nucleon spin structure

  4. The RHIC spin program • Longitudinal spin program: determination of the helicity distributions: • Gluon polarization ∆g(x) in the nucleon -- inclusive jet, hadrons -- di-jets, +jet • Flavor separation: quark & anti-quark polarization -- RHIC 500 GeV program (W prodction) • Hyperons spin transfer • Transverse spin program: • Single spin asymmetry AN (SSA) on 0,  • QCD mechanisms (Sivers, Collins, high-twist)

  5. Spin structure of nucleon • Spin sum rule (longitudinal case): Quark spin, Best known (~30%)-DIS Gluon spin, Poorly known, RHIC Orbital Angular Momenta Little known • Polarized parton densities: -> Transversity:（little know）

  6. STAR group @ SDU • 老师: 徐庆华，3月－5月在BNL访问 • 邓健（at BNL this year） • Topic: Hyperon spin transfer in pp • 研究生: 李璇 in BNL since 2009, • 预计2012年毕业 • Topic: Forward-Forward pi0 azimuthal • correlation at STAR 研究生: 张金龙，2011级硕士

  7. What is special with ? •  polarization can be measured in experiment via weak decay: • Λ->p-(Br64%), Λ->n0(Br36%) , -T.D.Lee, C.N.Yang(1957) Unit vector along proton momentum in ’srest frame. decay parameter: 0.642(p-) 0.65 (n0) polarization vector • ’s contain a strange constitute quark, whose spin is expected • to carry most of the  spin:  spin <=> s quark’s spin

  8. Longitudinal spin transfer in pp collisions • Longitudinal spin transfer : Provide access to pol.p.d.f. and fragmentation functions • Production of : - DLL of  is less sensitive to s, due to larger u and d quark frag. contributions. - DLL of - should be sensitive to s, but need more integrated luminosity.

  9. STAR上的超子极化重建 Time Projection Chamber enables PID Barrel EMC TPC BBC East BBC West Plus topological reconstruction: p  V0_vertex 4.2m V0_DCA • primary vertex for ||<~1.3

  10. STAR上的超子极化实验测量 STAR, PRD80(R),111102(2009)

  11. 关于超子极化转移分析的进展及计划 邓健于2011年8.23－24, 11月9－18参加了STAR 合作组年会，并报告了利用新数据关于超子纵向极化转移的新结果。 目前我们正在完善数据分析，包括MC模拟以及系统误差分析，明年参加国际会议报告结果，提交合作组准备发表。 已经开始探索其它超子 如的极化，以及超子 的横向极化。

  12. Forward-Forward pi0 correlation analysis 李璇, Nov.15, 2011 参加合作组会议，并报告 分析结果。PA of a STAR paper in preparation. CGC predicts suppression of back-to-back correlation. (1) The suppression of the height of the away side peak in the central dAu collisions suggests forward-forward correlations at low x are consistent with gluon saturation in nuclei. (2) The degree of broadening is consistent with multi-parton scattering in central dAu collisions associated with saturation. STAR Collaboration Meeting, Nov. 15, 2011 Xuan Li 12

  13. ~0mr crossing angl ~1.6mr crossing systematically increased thresholds for IP2 collisions ~2mr crossing -Xuan Li A Feasibility Experiment to Measure the Analyzing Powerfor Drell-Yan production at RHIC(-ANDY experiment) A critical test of QCD predictions Data taken in 2011

  14. Future plan: Lambda polarization in the forward region & related upgrade in ~5 years • Dec.12－16，STAR upgrade workshop at UCLA.

  15. Future plan: eRHIC？>2020 - EIC white paper, arXiv:1108.1713

  16. World data on pol. and unpol. deep-inelastic scattering

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