Transcript J-PARC Japan Proton Accelerator Research Complex

核子構造：J-PARC実験
Shin’ya Sawada
KEK
(High Energy Accelerator Research Organization, Japan)
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
1
メニュー

核子の形？
– ビジュアルでわかりたい straw man の素朴な疑問

実験
– これまでの実験
– これからの実験
• Fermilab E906
• J-PARC Proposals：主としてP04

施設
– ビームライン

まとめ
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
2
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 ρnm ~ 1.8 fm
Radius of a nucleon
~ 0.8 fm
average spacing at 3ρnm ~ 1.3 fm
“nucleons” held apart by
short range repulsion
but even in 208Pb, half the
nucleons are in the surface
or
– シークォーク(sea quark)の分布はどうなってる
の？
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
3
核子の形？（ビジュアル系な素朴な疑問）
– スピンでラベルしたときの形は？
• G. A. Miller, Phys. Rev. C68, 022201(R) (2003) S
• Spin dependent density operator
• Shapes of the proton. Proton spin is vertical
direction. Left column: quark spin parallel to
proton spin. Right column: quark spin antiparallel to proton spin. K (quark momentum):
1 to 4 GeV/c (from upper to lower).
• G. A. Miller, Phys. Rev. C76, 065209 (2007)
• Transverse momentum dependent parton
density and spin dependent density operator
q
q
Boer-Mulders Fn.（をxについて積分した関数）：
Drell-Yan で測定可能
• ゼロでないBoer-Mulders fn.  非球形のspin
dependent density
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
4
実験

レプトン－核子・核
– SLAC、DESY、CERN、…、Jlab

核子－核子・核
– 衝突型加速器：RHIC
– 固定標的実験: 米国フェルミ研
•
•
•
•
•
•
August 8, 2008
E605, E772 (-1988), E789 (-1991), E866 (-1996)
E906 (going)
p+p/d/A  mu+ mu- X ：ミュオン対の測定。
Drell-Yan 過程やQuarkonium生成を観測する。
比較的大きなｘ。
sea quark の分布に有感。
Shin'ya Sawada @ J-PARC
Workshop, KEK
5
Fermilab Experiments
Meson East Spectrometer
(E605/772/789/866)
Open-aperture
Closed-aperture
Beam-dump (Cu)
J/Ψ
J/Ψ
Ψ’
σ(J/ψ) ~ 15 MeV
σ(J/ψ) ~ 150 MeV
σ(J/ψ) ~ 300 MeV
6
Fermilab E866 Detector: 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
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
7
Physics with High-Mass Dimuons with unpol beam/target

Drell-Yan process
– Antiquarks in nuclei and nucleons
– Quark energy loss in nuclear medium
– Drell-Yan angular distributions
• Toward spin related structure

Quarkonium production
– Pronounced nuclear dependence
– Production mechanism and polarization
– Parton distribution in the nucleon

Heavy quark production
– Open charm production
– B-meson production
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK

Drell-Yan: ハドロン衝
突で最も単純な過程
– QCDからのfinalstate effectがない
– 偏極Drell-Yan実験は
これまで行なわれて
いない
8
Structure of the Nucleon Sea: Previous Data

pQCD – Gluon splitting? i.e.
NMC (Gottfried Sum Rule)

NA51 (Drell-Yan)

E866 (Drell-Yan)

August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
9
By What Process Is the Sea Created?

There is a gluon splitting
component which is symmetric

– Symmetric sea via pair production
from gluons subtracts off
– No Gluon contribution at 1st order
in s
– Nonperturbative models are
motivated by the observed
difference

A proton with 3 valence quarks
plus glue cannot be right at any
scale!!
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
10
By What Process Is the Sea Created?

Meson Cloud in the nucleon
Sullivan process in DIS
|pi = |p0i +  |Ni + |i + . . .

Chiral Models
Interaction between Goldstone
Bosons and valence quarks
|ui!|d+i and |di!|u-i


Instanton
Statistical Models
Models cannot explain d-bar < u-bar!
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
11
By What Process Is the Sea Created?

Meson Cloud in the nucleon
Sullivan process in DIS
|pi = |p0i +  |Ni + |i + . . .
Models cannot explain d-bar/u-bar < 1!
Perturbative sea
apparently dilutes
meson cloud
effects at large-x
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
12
Drell-Yan: A Laboratory for Sea Quarks
xtarget
xbeam
Detector acceptance chooses xtarget and xbeam.
 Fixed target ) high xF = xbeam – xtarget
 Valence Beam quarks at high-x.
 Sea Target quarks at low/intermediate-x
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
13
Drell-Yan: What do we really measure?

Measure yields of +- pairs from different targets

For each event measure 3-momentum of each 
Assume that it is a muon to get 4-momentum




Reconstruct M2, pT, p||
M2 = x1x2s,
xF = 2p||/s1/2 = x1 – x2
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
14
dbar/ubar at Large x using 50 GeV Protons

DY cross section is ~16
times larger at 50 GeV
than at 800 GeV.
d DY 1
 at fixed x1, x2
dx1dx2 s

J-PARC can measure dbar/u-bar at larger x.
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
15
実験プロポーザルとストラテジー

Fermilab E906: Main Injector with 120-GeV protons
– 2010-2012
– Mid x region, really d-bar/u-bar < 1??

J-PARC P04: Experiment with 30 and 50-GeV
protons
– 2012– 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.
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
16
Fermilab E906/Drell-Yan Collaboration
Abilene Christian University
Donald Isenhower, Mike Sadler,
Rusty Towell
Institute of Physics, Academia Sinica
Wen-Chen Chang, Yen-Chu Chen,
Da-Shung Su
Institutions under
negotiation
KEK
Ling-Tung University
Ting-Hua Chang
Los Alamos National Laboratory
Gerry Garvey, Mike Leitch,
Pat McGaughey, Joel Moss
Shinya Sawada
Kyoto
Argonne National Laboratory
John Arrington, Don Geesaman*,
Kawtar Hafidi, Roy Holt, Harold Jackson,
David Potterveld, Paul E. Reimer*,
Patricia Solvignon
KenIchi Imai, Tomofumi
Nagae
University of Colorado
Ed Kinney
Yuji Goto, Atsushi Taketani,
Yoshinori Fukao, Manabu
Togawa
Fermi National Accelerator Laboratory
Chuck Brown
Tokyo Tech
Maryland
Betsy Beise
Rutgers University
Ron Gilman, Charles Glashausser,
Xiaodong Jiang, Elena Kuchina,
Ron Ransome, Elaine Schulte
求む！（優秀な？）ポスドク！！
RIKEN
University of Illinois
Naomi C.R Makins, Jen-Chieh Peng
*Co-Spokespersons
August 8, 2008
Toshi-Aki Shibata,
Yoshiyuki Miyachi
People with underline are included
also in P04 and/or P24 at J-PARC.
Shin'ya Sawada @ J-PARC
Workshop, KEK
Texas A & M University
Carl Gagliardi, RobertTribble
Thomas Jefferson National
Accelerator Facility
Dave Gaskell
Valparaiso University
Don Koetke, Jason Webb
17
Advantages of 120 GeV Main Injector
The (very successful) past:
The future:
Fermilab E866/NuSea
Fermilab E906

Data in 1996-1997
1H, 2H, and nuclear targets
800 GeV proton beam

Cross section scales as 1/s





Data in 2010-12
1H, 2H, and nuclear targets
120 GeV proton Beam
– 7 x that of 800 GeV beam

Backgrounds, primarily from J/
decays scale as s
– 7 x Luminosity for same detector rate
as 800 GeV beam
Tevatron
800 GeV
Main Injector
120 GeV
50 x statistics!!
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
18
Spectrometer



Fermilabでのこれまでの財産を最大限生かして（使える部品はみん
な使って）作る。
800GeVでのこれまでの実験に比べ、長さを短く、apertureを出来る
だけ広く。
2台のbending magnet、pT kick 2.5GeV/cと0.5GeV/c。
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
19
E906でのd-bar/u-bar
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
20
P04: Measurement of High-Mass Dimuon
Production at the 50-GeV Proton Synchrotron
Collaboration
Abilene Christian University, Argonne National Laboratory, Duke University, High Energy Accelerator
Research Organization, University of Illinois at Urbana-Champaign, Kyoto University, Los Alamos
National Laboratory, Pusan National University, RIKEN, Seoul National University, Tokyo Institute of
Technology, Tokyo University of Science, Yamagata University
Collaboration members
J.K. Ahn, J. Chiba, Seonho Choi, D. Dutta, H. Gao, Y. Goto, L.D. Isenhower, T. Iwata, S.
Kato,M.J. Leitch, M.X. Liu, P.L. McGaughey, J.C. Peng, P. Reimer, M. Sadler, N. Saito, S.
Sawada,T.-A. Shibata, K.H. Tanaka, R. Towell, H.Y. Yoshida
needs 30 and 50 GeV, 1012 protons per sec.
Fermilab E906のSpectrometerをJ-PARCに運び、実験する。
 最初は30GeV陽子ビーム、続いて50GeV陽子ビーム。
 偏極標的や偏極ビームでの実験についても触れているが、これらについては本格的な
プロポーザルを準備中。

August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
21
Physics with High-Mass Dimuons with unpol beam/target

Drell-Yan process [50GeV]
– Antiquarks in nuclei and nucleons
– Quark energy loss in nuclear medium
– Drell-Yan angular distributions
• Toward spin related structure

Quarkonium production [30GeVでも]
– Pronounced nuclear dependence
– Production mechanism and polarization
– Parton distribution in the nucleon

Heavy quark production

Drell-Yan: ハドロン衝
突で最も単純な過程
– QCDからのfinalstate effectがない
– 偏極Drell-Yan実験は
これまで行なわれて
いない
– Open charm production
– B-meson production
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
22
Antiquarks in nucleons


dbar/ubar at Large x
using 50 GeV Protons.
J-PARC can measure dbar/u-bar at larger x.
1012 protons per spill (3 s)
50-cm long LH2 / LD2 targets
60-day runs for each targets
assuming 50% efficiency
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
23
Quark energy loss in nuclear medium




An understanding of partonic energy
loss in both cold and hot nuclear
matter is paramount to elucidating
RHIC data.
Pre-interaction parton moves through
cold nuclear matter and looses
energy.
Apparent (reconstructed) kinematic
values (x1 or xF) is shifted
Fit shift in x1 relative to deuterium
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
24
Quark Energy Loss with DY at 50 GeV

At 50 GeV, energy loss can be well measured.
– Fractional energy loss is larger at 50 GeV. Effect is amplified.

Possible to test the L dependence of the LPM effect from the A
dependence.
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
25
Drell-Yan angular distributions

Boer-Mulders function h1(x, kT2)
– angular distribution of unpolarized Drell-Yan
 2
 1  d   3  

2

1


cos



sin
2

cos


sin

cos
2

   d    4  
2
 
  

– correlation between transverse quark spin and quark
transverse momentum in an unpolarized proton
 
 
( Pˆ  k  )  S q q
( Pˆ  k  )  S q
q
2
2
N ( )  h1 ( x1 , k  ) 
 h1 ( x2 , k  ) 
M
M
 h1  h1 
    
 f1  f1 
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
26
Drell-Yan angular distributions
With Boer-Mulders function h1┴:
ν(π-Wµ+µ-X)~valence h1┴(π)*valence h1┴(p)
ν(pdµ+µ-X)~valence h1┴(p)*sea h1┴(p)
L.Y. Zhu,J.C. Peng, P. Reimer et al., Phys. Rev. Lett. 99, 082301(2007).
非偏極実験ながらスピンでラベルした核
子の構造にも手が届く！
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
27
Quarkonium production at 30 GeV

J/
– gluon fusion or quark-pair annihilation
– quark-pair annihilation dominant?
• must be confirmed experimentally…
• similar physics topics as Drell-Yan process
calculations by color-evaporation model
eq

l
q
J/
g qV
glV
q
August 8, 2008
l
Shin'ya Sawada @ J-PARC
Workshop, KEK
28
Quarkonium production at 30 GeV
800 GeV  ( p  d    X ) /  ( p  p    X )




L. Y. Zhu et al.,
Phys.Rev.Lett.100,
62301 (2008).
1
Drell  Yan :  pd / 2 pp  [1  d ( x) / u ( x)]
2
1
J / ,  :
 pd / 2 pp  [1  gn ( x) / g p ( x)]
2
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK


pdとppの比の（エネルギーによ
る）変化を測定することにより、
生成過程を明らかに出来る。
もしも30GeVでq+qbarが支配的
なら、J/Psi生成を核子構造の測
定に用いることが出来る。
29
Current Status

FNAL E906 Experiment
– Similar experiment using 120 GeV protons (p+p, p+d, and probably
p+A)
– Scientifically approved
– Preparation continues, seeking Japanese participation
– Expect experiment runs from 2010, for 2 years
– Apparatus is considered to be shipped to Japan after E906
– Reuse at J-PARC is being considered in the design

J-PARC Experiment even after E906
– Difference of beam energy should be important
• Lower energies lead to extension of large x region, clearer
measurement of energy loss, …
• Check of consistency
• Quarkonium production
– Also fruitful, and more complete understanding of the nucleon
structure with polarized beams in the future.
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
30
偏極ビーム・標的が利用可能になったら…

J-PARC dimuon 実験のスピン物理メニュー
– 縦偏極 ALL of Drell-Yan
• sea-quark 偏極のフレーバー非対称性
– 横偏極 AN of Drell-Yan
• Sivers関数（sin(-S) term）
• transversity分布関数 & Boer-Mulders関数（sin(+S) term）
– 横偏極 ATT of Drell-Yan
• transversity分布関数
– その他（30-GeV）
• J/: Drell-Yan と同様のメニュー?
• AN of open charm: Sivers関数
• (neutron-tagged Drell-Yan)
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
31
偏極ビーム・標的？


P24として提案→「実験と装置・施設を分けよ」→新しいプロポーザルへ。
unpolarized  polarized target  polarized beam
– polarized beam study by BNL & KEK groups
– possible locations of partial snakes in MR
First 30% snake
August 8, 2008
Second 30% snake
Shin'ya Sawada @ J-PARC
Workshop, KEK
32
ビームライン
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
33
Slow Extraction Beamline (Phase 1)
NP-HALL
56m(L)×60m(W)
50-GeV PS
Split Point
2% Loss
Switch Yard
T0 Target
0.5% Loss
A-Line
T1 Target
30% Loss
Beam Dump
750kW
Plan to extend the hall downstream (~50m)
in the Phase 2.
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
34
What is the High Momentum Beamline?
– Primary beams: proton (Phase 1), polarized proton and
heavy ions (future) up to 51 GeV/c.
– Secondary beams: proton, pion, kaon, etc.
– Vector meson production実験（四日市さん、明日）にも不可欠。
The radiation shielding of the SY tunnel
is designed so that 2% (15kW) loss
allowed at SM1.
Exp. setup could be staged.
~120m
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
35
Beamlines at the Hadron Hall
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
36
Oct.
Dec.
August 8, 2008
Neutrino
Shin'ya Sawada @ J-PARC
Workshop, KEK
37
R&D for a bent crystal system

Test experiment at KEK-PS (12-GeV proton)
Ceramic plate
viewCrystal
from above
p
crystal
deflection
angle
Al plate
CsI plate
Ceramic plates
CsI plate
(5x2.5cm)
deflected beam
ceramic plate
(10x10cm)
1012/s  107/s
main beam
Goniometer
bent crystal
±o
12GeV
protons
August±20
8, 2008cm
goniometer
Grant-in-Aid for a next step
R&D of high-mom beamline
is being applied:
• Bent crystal, ESS, …
Shin'ya Sawada @ J-PARC
Workshop, KEK
38
Cost & Schedule: Magnets from the World






Total cost if constructed from scratch: $5-8M??
We have no budget so far to construct a high
momentum beam line. But we are doing every
effort to construct it with as small cost as
possible, e.g. reuse of second-hand magnets…
Already from SLAC, Saclay, CERN, …
Large dipole magnets from ANL (previously
used for the polarized beam line at FNAL) are
under process!
The high momentum beam line can be
constructed by using some of these secondhand magnets.
The high momentum beam line can be
constructed even at the beginning of the hadron
hall operation from the viewpoint of the facility
design.
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
Large dipole magnets at the Meson
Pol beam line (FNAL)
39
Summary






核子の構造の研究は、ハドロン物理の王道（のひとつ）。
高エネルギーでの「小さいｘ」だけでなく、“低”エネルギーでの「大き
いｘ」領域も重要。
J-PARC 50GeV でのdimuon測定は、 Drell-Yan過程やJ/Psi生成
の観測を通じて、sea quark のフレーバー非対称性、パートンのエネ
ルギー損失、等々ハドロンをパートンレベルで研究するためにうって
つけの方法である。
Fermilabでは120GeVでのE906実験が進もうとしている。この実験
装置をJ-PARCに運び、より低いビームエネルギーで実験することを
目指している。
Dimuon測定は、偏極ビームや偏極標的が使用可能になると、より
物理的な意義が深まる。
「高運動量ビームライン」はこの実験を実現する上で必要不可欠な
ビームラインである。また、p+pphi+Xの実験にも必要である。「分
岐部」が技術的にもっとも困難であるが、地道にR&Dを進めている。
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
40
Physics with High-Mass Dimuons at J-PARC
Drell-Yan (at 50 GeV):
 d / u flavor asymmetry at large x
 Antiquark distributions in nuclei
 Quark energy loss in nuclei
J /  Production (at 30 or 50 GeV):
 J /  nuclear dependence
 d / u via J /  production
Spin physics with dimuons (mostly with polarized beam/target):
 Drell-Yan with polarized beam/target
(Sivers parton distributions, sea-quark polarizations, transversity)
 J /  with polarized beam/target
(Quark polarization, quark Sivers function)
 Unpolarized Drell-Yan decay angular distributions
(Boer-Mulder's distribution function)
August 8, 2008
Shin'ya Sawada @ J-PARC
Workshop, KEK
41