ssa measurements with primary beam at j-parc
DESCRIPTION
SSA Measurements with Primary Beam at J-PARC. Joint UNM/RBRC Workshop on “Orbital Angular Momentum” in Albuquerque February 25 th , 2006 Yuji Goto (RIKEN/RBRC). Outline. Introduction J-PARC spin physics with primary beam at J-PARC Drell-Yan experiment SSA measurements Summary. 295 km. - PowerPoint PPT PresentationTRANSCRIPT
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SSA Measurements with Primary Beam at J-PARC
Joint UNM/RBRC Workshop on
“Orbital Angular Momentum”
in Albuquerque
February 25th, 2006
Yuji Goto (RIKEN/RBRC)
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 2
Outline
• Introduction– J-PARC– spin physics with primary beam at J-PARC
• Drell-Yan experiment• SSA measurements• Summary
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 3
J-PARC at Tokai
TOKYO
KEK
JAERI
NARITA
KAMIOKA
Tsukuba
Tokai1 hour
295 km JAEA
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 4
J-PARC facility
Nuclear Transmutation
J-PARC = Japan Proton Accelerator Research Complex
3 GeV Synchrotron(25 Hz, 1MW)
Hadron Beam FacilityMaterials and Life Science
Experimental Facility
Neutrino to Kamiokande
50 GeV Synchrotron(0.75 MW)
500 m
Linac(330m)
Joint Project between KEK and JAEA
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 5
J-PARC facility
– The budget for about 2/3 of the entire project has been approved by the Japanese government from JFY2001 as Phase 1
– Phase 1 consists of major accelerator components and a part of experimental facilities
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 6
J-PARC parameters
– numbers in parentheses are for the phase 1
• Beam Energy : 50 GeV(30 GeV for Slow Beam)
(40 GeV for Fast Beam)
• Repetition: 3.4 ~ 5-6 sec• Flat Top Width : 0.7 ~ 2-3 sec• Beam Intensity: 3.3x1014 ppp, 15 mA
(2×1014 ppp, 9 mA)
ELinac = 400 MeV (180 MeV)
• Beam Power: 750 kW (270 kW)
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 7
J-PARC schedule
Now
first beam for the nuclear-particle experiments in
JFY2008 first beam for theneutrino experimentsin JFY2009
call for proposals started: deadline April 28, 2006
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 8
J-PARC facility
Hadron ExperimentalFacility
Number of Users: about 600
(about 1/3 from Japan)
September, 2005
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 9
Hadron experimental hall (phase 1)
BeamDump
A-Line
Experimental Area
Test Beam
(on the guide rail
for Phase 2)
beamlines for secondary beam experiments at the beginning of the phase1
area for primary beam experiments
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 10
Introduction
• Origin of the nucleon spin 1/2 ?
– polarized DIS experiments showed the quark-spin contribution is only 10-30%
– gluon-spin contribution ?– orbital angular momentum ?
• Scaling violation in polarized DIS
Lg 2
1
2
1
(th)(syst)(stat)99.0)GeV 1( :SMC 43.145.0
42.022.0
17.131.0
22
Qg
1.1(syst)(stat)8.06.1)GeV 5( :E155 22 Qg
P.L. Anthony et al., PLB 493, 19 (2000).
B. Adeva et al., PRD 58, 112002 (1998).
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 11
Introduction
• Semi-inclusive DIS– high-pT hadron pairs
– open charm production
lepton beam or
or nucleon target
*
gluon
heavy flavor
COMPASS high pT hadron pairs(Q2 < 1(GeV/c)2)PLB 633 (2006) 25.G/G = 0.024 0.089(stat)0.057(syst)at xg = 0.095 (2 ~ 3(GeV/c)2)
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 12
Introduction
• Present target at RHIC – gluon-spin contribution– polarized hadron collision– leading-order gluon measurement
proton beam
proton beam
or
or
gluon
photon
proton beam
proton beam
or
or gluon
gluonheavy flavor
direct photon production heavy-flavor production
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 13
Introduction• Gluon contribution – PHENIX ALL of 0
– PHENIX official statement• conclusively excludes GRSV maximal scenario• consistent with GRSV standard and GRSV g=0 input scenarios
– Personal statement• ~1-sigma region: g < 0.4• orbital angular momentum measurements should be developed for
the final solution
GRSV-max: g = 1.84
GRSV-std: g = 0.42at Q2=1(GeV/c)2
best fit to DIS data
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 14
Introduction
• Orbital angular momentum– hint in hadron reactions
– asymmetries in angular distribution of semi-inclusive hadron production at polarized DIS exps
STAR collaboration, hep-ex/0310058, Phys. Rev. Lett. 92 (2004) 171801
STARSTAR
Fermilab E704: Elab = 200 GeV STAR at RHIC: s = 200 GeV
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 15
Drell-Yan experiment
• Fermilab E866/NuSea and E906 at MI– closed geometry
Fermilab Elab = 800 GeV2×1012 protons / 20 sec
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 16
Drell-Yan experiment
• Ratio of p+d cross section to p+p d-bar/u-bar
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 17
Experimental apparatus– two vertically bending magnets with pT kick of 2.47 GeV/c and 0.5
GeV/c– closed geometry– tracking is provided by three stations of MWPC and drift chambers– muon id and tracking are provided– 2x1012 50 GeV p/spill– based on the Fermilab spectrometer for 800 GeV, the length can be
reduced but the aperture has to be increased
tapered copper beam dump andCu/C absorbers placed within the first magnet
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 18
Simulation studies
• Expected Drell-Yan counts for a two-month p+d run at 50 GeV– 2x1012 protons/spill– 50-cm long liquid
deuterium target– assume 50 percent
overall efficiency
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 19
Possible layout of the hadron hall
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 20
Drell-Yan experiment
• ALL sea quark polarization
chiral quark solitonmodel prediction
120-day run
GS-CGS-AGRSV
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 21
SSA on Drell-Yan
– no final-state effect
– sensitive to Sivers effect at low qT: qT << Q
(from Xiangdong Ji’s slide at J-PARC hadronstructure workshop at KEK, December, 2005)
integrated over qT
Sivers function fit from Vogelsang & Yuan: PRD 72, 054028 (2005).
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 22
SSA on Drell-Yan
– sensitive to higher-twist effect at high qT: QCD << qT
(from Xiangdong Ji’s slide at J-PARC hadronstructure workshop at KEK, December, 2005)
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 23
SSA measurement of pions
• Forward pions with a polarized target– backward AN (xF < 0)
– sensitive to the gluon Sivers effect at fixed-target exp. energies– not very sensitive at collider energies
RHIC: s = 200 GeVElab = 200 GeV s = 19.4 GeV
M. Anselmino, U. D’Alesio, F. Murgia, et al.
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 24
SSA measurement of pions
• Forward pions with a polarized target– start with simple forward spectrometer with some
particle-ID detectors– EM calorimeter for0
• Forward pions with a polarized beam
– forward AN (xF > 0)– confirmation of E704 asymmetries at smaller energies
• BNL-E925 at Elab = 22 GeV confirmed for charged pions
• pT dependence will give more information
without dump and absorbers
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 25
SSA measurement of D-mesons
– gluon fusion or quark-pair annihilation
– no single-spin transfer to the final state
– sensitive to initial state effect: Sivers effect
• to be measured at RHIC: PHENIX with silicon upgrade (2009)
– collider energies: gluon-fusion dominant
• sensitive to gluon Sivers effect
– fixed-target energies: quark-pair annihilation dominant
• sinsitive to quark Sivers effect
– complementary
J-PARC: Elab = 50 GeV
M. Anselmino, U. D’Alesio, F. Murgia, et al.
RHIC: s = 200 GeV
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 26
D-meson– cross section
• PYTHIA (6.228) study with PHENIX tune (<kT> = 1.5 GeV/c, Mc = 1.25 GeV/c2, K-factor = 3.5, Q2 = s)
• J-PARC: 3-4 order smaller cross section than that at RHIC– can be compensated by higher intensity/luminosity at J-PARC ?
15101
0.1
15101
0.1consistent at fixed-targetregion, too
smaller yield (same resultas Laurenco’s study)
Wohri and Lourenco
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 27
D-meson– silicon detectors to identify second decay vertex– yield study
• 109 proton/sec beam• 10% target• 2×1033 cm-2sec-1
• × 1 week = 103 pb-1
• acceptance 0.05 – 0.3 to cover forward/mid-rapidity/backward
xF xF-1 -11 1
pT
1.5 GeV/c
pT > 1.5 GeV/cD0 yield 5.5×106 D0
for 103 pb-1
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 28
D-meson
– efficiency study necessary• decay• DCA cut efficiency
– detector study necessary• radiation hardness• D-meson identification: E/E in silicon ?• triggering
– beam intensity / luminosity as high as possible• depending on radiation hardness of detectors,
occupancy/multi-collision capability, etc.
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 29
Other SSA measurements
• Charmonium– J/ and c
• The most forward neutron– found at RHIC s = 200
GeV– zero-degree calorimeter– large asymmetries in
collider energies• AN ~ -12% at xF > 0.2 and pT
< 0.3 GeV/c at RHIC
– physics implication ?
5m1m
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 30
Other subjects
• Gluon polarization at large-x– charmonium ALL
• J/, c0, c1, c2
c2: gluon-fusion dominant– produced mainly from helicity 2 state of the gluon
fusion– sensitive to g(x)
• identified measurement is possible only in the fixed-target experiments
– low photon energy of c + J/ decay
– direct-photon ALL
• Transversity– Drell-Yan ATT
• “Fields” effect– Drell-Yan ALL(qT)
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 31
Under discussion
• Polarized proton acceleration– study group was formed– installation of Siberian snakes seems possible– technical note in preparation
• Polarized target• More discussion consideration and R&D
– Drell-Yan apparatus +– silicon detector– calorimeter
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 32
Detector
• NA60 spectrometer– example of silicon spectrometer + muon detector– charm-identification with muon-coincidence
CERNElab = 158 GeV2×109 protons / 5 sec
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 33
Detector
• PHENIX upgrades– technically important– silicon pixel & strip (stripixel) 2008 installation
• RIKEN/RBRC group is leading
– Si/W calorimeter• RIKEN/RBRC group is participating and supporting
80cm
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February 25, 2006 Yuji Goto (RIKEN/RBRC) 34
Summary
• For the spin physics program with primary beam at J-PARC, study group for the polarized proton acceleration and the physics experiment were formed, and discussions are underway
• Measurement of the orbital angular momentum component in the nucleon is one of the most important goal of the spin physics program at J-PARC
• Drell-Yan experiments are planned– SSA measurements of Drell-Yan, pions, D-mesons, etc.– gluon polarization at large-x, transversity, etc.
• Physics and detector studies are ongoing• Collaboration with many groups in the world is very
important