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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?. - PowerPoint PPT Presentation
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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)
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Relativistic Heavy Ion Collider (RHIC) at Brookhaven
-- also the first polarized pp collider
RHIC BRAHMSPHOBOS
PHENIXSTAR
AGS
TANDEMS
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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
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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)
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Quark spin, Best known (~30%)-DIS
Gluon spin,Poorly known,RHIC
Orbital Angular MomentaLittle known
• Spin sum rule (longitudinal case):
Spin structure of nucleon
€
q(x,Q2) = q+(x,Q2)+q−(x,Q2)
€
−
€
+
• Polarized parton densities:
-> Transversity: ( little know )
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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
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What is special with ?
decay parameter: 0.642(p-)
0.65 (n0)
Unit vector along proton momentum in ’s rest frame.
polarization vector
• polarization can be measured in experiment via weak decay:
Λ->p-(Br64%), Λ->n0(Br36%) , -T.D.Lee, C.N.Yang(1957)
• ’s contain a strange constitute quark, whose spin is expected to carry most of the spin:
spin <=> s quark’s spin
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Provide access to pol.p.d.f. and fragmentation functions
• Longitudinal spin transfer :
Longitudinal spin transfer in pp collisions
• 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.
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BBCEast
Barrel EMC
BBC West
TPC
p
V0_vertex
V0_DCA
r_
Time Projection Chamber enables PID
Plus topological reconstruction:
4.2m
for ||<~1.3
• primary vertex
STAR 上的超子极化重建
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STAR, PRD80(R),111102(2009)
STAR 上的超子极化实验测量
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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。
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Forward-Forward pi0 correlation analysis
Xuan Li 12
CGC predicts suppression of back-to-back correlation.
STAR Collaboration Meeting, Nov. 15, 2011
(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.
李璇 , Nov.15, 2011参加合作组会议,并报告分析结果。 PA of a STARpaper in preparation.
A Feasibility Experiment to Measure the Analyzing Power for Drell-Yan production at RHIC
(-ANDY experiment)
A critical test of QCD predictions
~2mr crossing ~1.6mr crossing
~0mr crossing angl
systematically increased thresholds for IP2
collisions
Data taken in 2011
-Xuan Li
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Future plan: Lambda polarization in the forward region & related upgrade in ~5 years
• Dec.12 - 16 , STAR upgrade workshop at UCLA.
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Future plan: eRHIC ? >2020
- EIC white paper, arXiv:1108.1713
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World data on pol. and unpol. deep-inelastic scattering
€
F2(x) = e i2
i
∑ xq i(x )