J-PARC ハドロン実験施設 と そこでの核子構造研究の可能性 Shin’ya Sawada 澤田 真也 KEK (High Energy Accelerator Research Organization, Japan) January 7, 2011 Shin'ya Sawada 1
Contents Overview of J-PARC Hadron Facility Nucleon Structure Research with Drell-Yan – A series of Fermilab experiments New Drell-Yan Experiments – E906/SeaQuest and J-PARC P04 Toward New Step of Structure Study – 2D to 3D, importance of the orbital angular momentum – Possibility of spin-related experiments at J-PARC R&D – High momentum beam line – Polarized target Possibility of the Facility – 40GeV? Pol. beam? Pi beams? Sumnmary January 7, 2011 Shin'ya Sawada 2
J-PARC Fa Facilit ility Linac ac (KE KEK/ K/JAE JAEA ） So South th to to North th 3 GeV 3 GeV Neut eutrino no B Bea eams Synchrot rotron ron (to to K Kam amioka) a) Mate Material als an and Life Experim Expe imental Fa l Facilit ility JFY2007 B 2007 Bea eams Ha Hadr dron Exp. Exp. JFY2008 B 2008 Bea eams January 7, 2011 Shin'ya Sawada 3 Facilit Fa ility JFY2009 B 2009 Bea eams Bird’s eye photo in January of 2009
Hadron Hall (Phase 1) NP-HALL 56m(L) × 60m(W) 50-GeV PS A-Line Switch Yard Split Point T1 Target T0 Target Beam Dump 2% Loss 30% Loss 0.5% Loss 750kW January 7, 2011 Shin'ya Sawada 4
Hadron Experimental Hall (Phase I) A-Line Beam Dump High Momentum Beamline Extension January 7, 2011 Shin'ya Sawada 5 in Phase II 56 m
North Side: K1.8, K1.8BR SKS SKS-System System Beautiful K/ π separation has been achieved in 2009 January 7, 2011 Shin'ya Sawada 6 DORAEMON DORAEMON-System System
SKS Spectrometer Ｋ 1.8 & ＳＫＳ Q13 Q12 K1.8 Beam Spectrometer D4 Q11 Q10 January 7, 2011 Shin'ya Sawada 7
2010 年 9 月 28 日ハドロンホール南側 January 7, 2011 Shin'ya Sawada 8
Oct. 15, 2010 January 7, 2011 Shin'ya Sawada 9
High-Momentum Beam Line Separated at the SM1 in the switchyard. 2% beam loss is allowed at the SM1. “Special” branching device for primary proton beams at the SM1. Thin target for seconadry beams at the SM1. SM1 January 7, 2011 Nov 。 30, 2010 Shin'ya Sawada Shin'ya Sawada 10 10
Contents Overview of J-PARC Hadron Facility Nucleon Structure Research with Drell-Yan – A series of Fermilab experiments New Drell-Yan Experiments – E906/SeaQuest and J-PARC P04 Toward New Step of Structure Study – 2D to 3D, importance of the orbital angular momentum – Possibility of spin-related experiments at J-PARC R&D – High momentum beam line – Polarized target Possibility of the Facility – 40GeV? Pol. beam? Pi beams? Sumnmary January 7, 2011 Shin'ya Sawada 11
核子の形？（ビジュアル系な素朴な疑問） 核子＝３つのバレンスクォーク (?) – 形は？球形？？“均一”？？？ – 核の中の核子の形は？ average spacing at ρ nm ~ 1.8 fm Radius of a nucleon ~ 0.8 fm average spacing at 3 ρ nm ~ 1.3 fm “ nucleons” held apart by or short range repulsion but even in 208 Pb, half the nucleons are in the surface – 海クォーク (sea quark) の分布はどうなって るの？ January 7, 2011 Shin'ya Sawada 12
Drell-Yan 過程 陽子－陽子衝突によるドレル・ヤン過程 ミューオン－陽子深非弾性散乱 陽子 陽子 陽子 レプトン散乱は 物質（例：陽子 ) 中 のクォーク分布の最適プローブ γ ∗ γ ∗ q q Drell-Yan 過程は 反クォーク工場：反クォーク（海クォーク）分布の最適プローブ January 7, 2011 Shin'ya Sawada 13
Drell-Yan 測定の例： Fermilab Experiments Meson East Spectrometer (E605/772/789/866) Open-aperture Closed-aperture Beam-dump (Cu) J/ Ψ J/ Ψ σ (J/ ψ ) ~ 300 MeV Ψ ’ σ (J/ ψ ) ~ 150 MeV σ (J/ ψ ) ~ 15 MeV January 7, 2011 Shin'ya Sawada 14
Drell-Yan 過程の運動学 + µ − µ For each event measure 3-momentum of each µ Assume that it is a muon to get 4-momentum γ , p || γ Reconstruct M 2 γ , p T M 2 γ = x 1 x 2 s, γ /s 1/2 = x 1 – x 2 x F = 2p || January 7, 2011 Shin'ya Sawada 15
Drell-Yan 過程の運動学 Detector acceptance chooses x target (x 1 ) and x beam (x 2 ). Fixed target: high x F = x beam – x target Valence Beam quarks at high-x. Sea Target quarks at low/intermediate-x x target x beam While previous experiments were done at 800 GeV, E906 uses 120-GeV Main Injector beams. – Cross section scales as 1/s • 7 x that of 800 GeV beam Backgrounds, primarily from J/ ψ decays scale as s – • 7 x Luminosity for same detector rate as 800 GeV beam 50 x statistics!! January 7, 2011 Shin'ya Sawada 16
Fermilab E866 Spectrometer: Long History E605: 1978-1985 US-Japan – Study of single and pair production of leptons and hadrons at very high transverse momenta E772: 1986-1988 – Nuclear dependence of DY and quarkonium production E789: 1989-1991 – Search for two body decay of heavy quark mesons E866/Nusea: 1993-1996 – Determination of d-bar/u-bar ratio of the proton via DY January 7, 2011 Shin'ya Sawada 17
海クォークの構造：これまでの実験データ pQCD – Gluon splitting? i.e. NMC (Gottfried Sum Rule) ∫ 1 = − p n S [( F ( ) x F ( )) / ] x x dx G 2 2 0 1 2 ∫ 1 = + − ( u ( ) x d ( )) x dx p p 3 3 0 1 = = ( i f u d ) Fitting の結果 p p 3 S G = 0.235 ± 0.026 NA51 (Drell-Yan) E866 (Drell-Yan) January 7, 2011 Shin'ya Sawada 18
海クォークの構造 グルーオン splitting だけでは dbar=ubar しか説明できない。 「中間子雲」モデル – dbar>ubar どのような描像も dbar<ubar は説明できない！ January 7, 2011 Shin'ya Sawada 19
Fermilab E906/SeqQuest 実験 目的： 0.25 < x < 0.45 で dbar/ubar を測定し、より広い 範囲での dbar/ubar とその x 依 存性を明らかにする。 陽子ビーム： FNAL Main Injector からの 120GeV ビーム – 2x10 12 /sec on target スペクトロメータ : 既存の資産を 最大限生かしながら建設す る。 Tevatron – 日本グループは Station 3 を主と 800 GeV して担当する。 Main Injector 120 GeV January 7, 2011 Shin'ya Sawada 20
Advantages of 120 GeV Main Injector The (very successful) past: The future: Fermilab E866/NuSea Fermilab E906 Data in 1996-1997 Data in 2010-12 1 H, 2 H, and nuclear targets 1 H, 2 H, and nuclear targets 800 GeV proton beam 120 GeV proton Beam Cross section scales as 1/s – 7 x that of 800 GeV beam Backgrounds, primarily from J/ ψ Tevatron decays scale as s 800 GeV – 7 x Luminosity for same detector rate Main Injector 120 GeV as 800 GeV beam 50 x statistics!! January 7, 2011 Shin'ya Sawada 21
Drell-Yan Spectrometer for E-906/SeaQuest (25m long) Station 3 (Hodoscope array, drift chamber track.) Station 1 (hodoscope array, MWPC track.) Iron Wall (Hadron absorber) Station 4 KTeV Magnet (hodoscope array, prop (Mom. Meas.) tube track.) Station 2 Solid Iron Magnet Targets (hodoscope array, (focusing magnet, (liquid H 2 , D 2 , January 7, 2011 Shin'ya Sawada drift chamber track.) 22 hadron absorber and and solid targets) beam dump) 22
Fermilab Seaquest Timelines • Fermilab PAC approved the experiment in 2001, but experiment was not scheduled due to concerns about “proton economics” • Stage II approval in December 2008 • Expect to start running around Thanksgiving for 2 years of data collection Expt. Experiment Experiment Exp. Funded Construction Runs Runs 2013 2014 2009 2012 2008 2010 2011 Beam: low intensity low intensity low intensity w/ Tevatron extension Apparatus available for future programs at, e.g. Fermilab, J-PARC or RHIC ➡ significant interest from collaboration for continued program January 7, 2011 Shin'ya Sawada 23 23
実験プロポーザルとストラテジー Fermilab E906/SeaQuest: Main Injector with 120- GeV protons – 2010-2013 – Mid x region, really d-bar/u-bar < 1?? J-PARC P04: Experiment with 30 and 50-GeV protons – 2014- – Experimental apparatus mainly from E906 – Ep = 30 GeV at the beginning • J/Psi physics – Ep = 50 GeV at the next stage with unpol beams for higher x – Polarized target and / or polarized beams • New proposal is under preparation. January 7, 2011 Shin'ya Sawada 24
Antiquarks in nucleons dbar/ubar at Large x using 50 GeV Protons. J-PARC can measure d-bar/u-bar at larger x. 12 10 protons per spill (3 s) 50-cm long LH / LD targets 2 2 60-day runs for each t argets assuming 50% efficienc y January 7, 2011 Shin'ya Sawada 25
Motivation of an experiment at J-PARC Muon pair measurement from p+p, p+d, and p+A reactions Drell-Yan – Sea quark flavor asymmetry at larger x target – Spin-labeled structure at large x target – Paton energy loss in cold nuclear matter J/Psi – production mechanism – nuclear dependence Open charm and others If polarized target more spin structure (P24) And if polarized beam much more spin structure (P24) January 7, 2011 Shin'ya Sawada 26
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