projector test
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APS-DNP 2004 Session DA: Probing the Gluonic and Quark Structure of Matter. projector test. APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004. DA Probing the Gluonic and Quark Structure of Matter. - PowerPoint PPT PresentationTRANSCRIPT
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projector test
APS-DNP 2004 Session DA: Probing the Gluonic and Quark Structure of Matter
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DA1. First Experiments with a Polarized Hydrogen Jet Target in RHIC
Willy Haeberli
Department of Physics, University of Wisconsin-Madison
DA Probing the Gluonic and Quark Structure of Matter
Measuring the Polarization of High-Energy Protons
WHY?HOW?
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
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K. Rith DIS 2004
DIS of polarized HE leptons (e,) from polarized nucleons atSLAC, CERN, HERA: Good agreement with
two very different experimental methods……….
What accounts for the spin of the nucleon?
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
The (old) proton spin puzzle:Only ~(20±4)% of proton spinisaccounted for by spins ofquarks and antiquarks
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two 60 cm long Target-Containerswith opposite polarization
superconductive
Solenoid (2.5 T)
3He – 4He Dilution refrigerator (T~50mK)
Dipole (0.5 T)
COMPASS polarized LiD target
E = 160 GeV, pB -76% 1.8*107 /sec (time ave)polarized LiD-target , pT 50%Luminosity: 5*1032 cm-2 s-1
Polarization: ~50%Dilution 40%
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HERMES internal target
Factor 100 gain fromuse of “storage cell” (S. Price)
Polarized H,D injection
To H,D polarimeter
. . .
Pure polarised gas targets: H, D, target polarisation: pT 85%target thickness 1014 H/cm2
Luminosity: 6*1033 cm-2 s-1(D @ 50 mA) spin reversal every 120 sec
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0.1 Gluon? Orbital?
Gluons: key contributor to the proton spin?
€
1
2= + Sq + Sg + Lq,g
slide adapted fromW. Vogelsang (BNL)
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Gluons: Measurements of G/G
xg
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
from F. H. Heinsius, COMPASS Collab - DIS April 2004 PHENIX and STAR at RHIC will measure G by collisions of longitudinally polarized HE protons - ALL
RHIC: c.m.energies up to 500 GeV
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€
ALL =1
Pbeam2
N↓↑ − N↑↑
N↓↑ + N↑↑
RHIC experiments will measure G
BUT HOW DOES ONE KNOW Pbeam?
Colliding polarized protons couple directly to gluons (rather than via charge) - measure parton asymmetries.
Measure polarization of gluons through , jets, pi’s, heavy quarks. G. Bunce DUBNA-SPIN-03
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The RHIC Complex 50 s 500 GeV
STARPHENIX
Spin Rotators
20% Snake
PHOBOS SiberianSnakes
present performance: L=4x1030s-1cm-2, Pbeam ~ 40%
5% Snake 0.7 1011 pol. protons/bunch56 bunches
BRAHMS & PP2PP
AGS
LINACBOOSTER
Pol. Proton Source
Siberian Snakes
200 MeV polarimeter Rf Dipoles
AGS p-C polarimeter
RHIC p-C polarimeters
absolute pppolarimeter
+ - + - + - + + - - + +
RHIC
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• What mechanism is sensitive to P at high energy? • Need to know analyzing power A.
€
€
ˆ n = ˆ k in × ˆ k out
€
σL,R=σ0(1±A(θ)P)
€
Measuring polarization of proton beam
€
"asymmetry" ε = PA =NL − NR
NL + NR
Reverse P to eliminate instrumental asymmetry
€
ε =PA =R −1
R +1 with R =
(NL /NR )↑
(NL /NR )↓
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
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Magnetic Moment Scattering
Mott (1929), J. Schwinger (Phys. Rev. 73, 1948)
+
Analyzing power in small-angle neutron scattering…..
“It is the purpose of this note to suggest a second mechanism for polarizing fast neutrons - the spin-orbit interaction arising form the motion of the neutron magnetic moment in the in the nuclear Coulomb field.”
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
€
r ⋅
rB →
r l ⋅
r s
Spin-orbit coupling:
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APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
Coulomb-nuclear interference (“CNI”)
Phil. Mag. 1, 175 (1956)
10
10%
σ P U(n,n)U100 MeV
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FNAL E704 200 GeV/cPhys. Rev. D48, 3026 (1993)
AN vs momentum transfer
Polarized protons from Hyperon decay (low rate)
CNI Analyzing Power in High-Energy pp Scattering
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E950@BNLp = 21.7 GeV/cPhys. Rev. Lett. 89 (2002)
with hadronicspin-flip
no hadronicspin-flip
momentum transfer [(GeV/c)2]
CNI Analyzing Power p-Carbon Scattering
calibration only at 22 GeV/csmall AN
Scale uncertainty ~30%Unknown energy dependenceBut large count rates
need for accurate absolute AN measurement
A=2(Re(g∗h)g
2+h2
M(θ,φ)=g(θ)+h(θ)(ˆ n ⋅r σ )
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Beam Polarization Calibration
• Measure asymmetry εtgt when unpolarized beam is scattered from polarized target of KNOWN polarization Pt - measures A
• Measure asymmetry εbeam when polarized beam is scattered from unpolarized target
Elastic scattering of IDENTICAL particles (pp): beam analyzing power = target analyzing power (Change in reference frame)
€
εtgt = Pt A
€
Pb = Pt εbeam ε tgt( )
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
Both experiments done simultaneously
€
εbeam = (−)Pb A
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+1
0
-1
+1/2 - 1/2
- 1/2 +1/2
mI
P
€
B ∝ r2
r F r = ±k
r r
The Polarized Target - Principle
rH
H2
acceptance angle
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. . . . . .and Practice
• Cooled dissociator nozzle to reduce v and v-spread.• recombination: dissociation depends on gas flow and nozzle temp • Beam attenuation: rest gas and intrabeam scattering• Magnet design (taper, lengths, z-position) needs: velocity distribution, dissociator H output vs gas flow, nozzle T beam forming geometry• differential pumping
OPTIMIZATION: COMPUTER MODELLING
rare-earth perm. magnets, pole tip 1.5T, max |B|/ r =6T/cm)
overall design:Tom Wise, UW
rH
H2
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24 sectors separatingmagnets with 1.5 T field at the pole tips.
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
H-jet sextupole separation magnet system.
0 0.5m 1m 1.5m
p-beam
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separationmagnets(sextupoles)
H2 dissociator
Polarimeter
focusingmagnets(sextupoles)RF transitions
holding fieldmagnet 1.2 kG
recoil ChamberSilicon Det.
(1),(2)
Pz+ : (1),(4) (transition (2)(4))
Pz- : (2),(3) (tranistion (1)(3))
Hyperfine state (1),(2),(3),(4)
The Polarized H-jet at RHIC
Beam intensity:(1.2±0.2)1017H/s
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Nuclear polarization of H-atoms
Efficiency of RF transitions: (99.7±0.2)%
ideal proton polarization for B=1.2kG: P = 0.960
plus ~3% dilution from H2
P = 0.924 ±2%
bunch-field depolarization <0.1%
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
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Scattering Chamber (top view)
H-jet profile
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
Target thickness:(1.3 ±0.2)x1012 H/cm2
80 cm
P RECOIL H-JET
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Recoil detectors (blue beam):
6 detectors 70x64 mm 16 strips (5 mrad each)
Measure• Energy: 1~7MeV resolution < 50 keV• TOF: 16~80 ns resolution < 2 ns• Angle: 10~100 mrad (89.5 - 84O)
resolution 5 mradB
H jet
Recoil Detectors
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
RHIC beam
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Tim
e of
flig
ht
CNI peak AN 1 < E < 2 MeV
Recoil protons elastic pp
`0 1 2 3 4 5 MeV
Recoil energy vs. time-of-flight
0
sourcecalibration
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Strip #1 16T
R M
eV
241AmTOF < +/-8 ns
TOF vs TR Si detector of first 8 channels
TR
TO
F
analysis
Recoil energy strip by strip 241Am
Identifying recoil protons vs recoil angle (=strip #)
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pp elastic 100 GeV/c
FNAL E704 200 GeV/c
no hadronic spin-flip
data to analyze
pp Analyzing Power 100GeV/cAN vs. momentum transfer
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Polarization of 100 GeV Beam
• study systematic errors and improve statistics for absolute calibration accuracy ±5%• analyze wider t-range to study pp interaction • bunch field depolarization with 110 bunches• improved measurement of H2 contamination of H-beam• measure beam polarization at injection• measure blue and yellow beam polarization
Plans:
€
Pbeam = Pt arg et
εbeam
ε t arg et
= 0.39 ± 0.03 (stat) ~106 pp events
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Wisconsin:, T. Wise, M. Chapman, W.H.
BNL: A. Bravar, G. Bunce, R. Gill, Z. Li,
A. Khodinov, A. Kponou, Y. Makdisi,
W. Meng, A. Nass, S. Rescia, A. Zelenski
Kyoto: H. Okada, N. Saito
ITEP-Moscow: I. Alekseev, D. Svirida
IUCF: E. Stephenson
RIKEN-BNL: O. Jinnouchi,
Rikkyo U: K. Kurita
ANL: H. Spinka
H-Jet collaborators:
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1.26 km
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no hadronic spin-flip
pp elastic 100 GeV/c
FNAL E704 200 GeV/c
data to analyze
Recoil angle 89.5o
Recoil energy 0.53 MeV 5.3MeV
pp Analyzing Power 100GeV/cAN vs. momentum transfer
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Plans
Plans:• improve statistics, study systematic errors for absolute calibration accuracy ±5%• analyze wider t-range to study pp interaction • bunch field depolarization with 110 bunches• improved measurement of H2 contamination of H-beam• measure beam polarization at injection• measure blue and yellow beam polarization
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
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RHIC pp accelerator complex
BRAHMS & PP2PP (p)
STAR (p)PHENIX (p)
AGS
LINACBOOSTER
Pol. Proton Source500 A, 300 s
Spin Rotators
Partial Siberian Snake
Siberian Snakes
200 MeV Polarimeter AGS Internal Polarimeter
Rf Dipoles
p-C PolarimetersAbsolute Polarimeter (H jet)
0.7 1011 pol. protons/bunch56 bunches
AGS pC Polarimeters
Strong AGS Snake
+ - + - + - + + - - + +
L=4x1030s-1cm-2, Pbeam ~ 40%
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€
ALL =1
Pbeam2
N↓↑ − N↑↑
N↓↑ + N↑↑
RHIC experiments will measure G
BUT HOW DOES ONE KNOW Pbeam?
Colliding polarized protons couple directly to gluons (rather than via charge) - measure parton asymmetries.
Measure polarization of gluons through , jets, pi’s, heavy quarks. G. Bunce DUBNA-SPIN-03
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HERMES internal targetPure polarised gas targets: H, D,
target polarisation: pT 85%
Luminosity: 6*1033 cm-2 s-1(D @ 50 mA)
spin reversal every 120 sec
Factor 100 gain fromuse of storage cell
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The Data (a sample)
num
ber
of e
vent
s (a
. u.
)
ReconstructedMissing Mass2
FWHM ~ 0.1 GeV2
SimulationMM2
FWHM ~ 0.1 GeV2
Inelastic Threshold
GeV2
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u+d+s 0,20 0,04 ..
QCD analysis of Q2 dependence:
K. Rith DIS 2004
DIS of polarized HE leptons frompolarized nucleons atSLAC, CERN, HERA:The (old) proton spin puzzle:Only ~20% of proton spin isaccounted for by spins ofquarks and antiquarks
Two experimental methods:• thick solid polarized target + low intensity e or beam• Thin polarized gas target + high intensity beam
What accounts for the spin of the nucleon?
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
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preliminary
Non-hadron spin flip
(Re r5= -0.02)
(Re r5= +0.02)
Comparison with some models (Not Fitting)
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• Demonstrated feasibility of accurate beam polarization calibration at high energy• calibration of p-C polarimeter• measurement of pp AN (8 angles, ±~10%)• H-jet does not interfere with p-beam life time• 3% measurement requires <200 hrs with improved beam intensity• method covers entire energy range of RHIC
one important step towards a precise determination of G……
CONCLUSIONS:
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Solenoidal field Axial Field
STAR€
ALL =1
Pbeam2
N↓↑ − N↑↑
N↓↑ + N↑↑
RHIC experiments will measure G
BUT HOW DOES ONE KNOW Pbeam?
PHENIX
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Polarization of 100 GeV Beam
€
Pbeam = Pt arg et
εbeam
ε t arg et
= 0.40 ± 0.03
Plans:• analyze wider t-range to study pp intercaction• improve statistics • bunch field depolarization with 110 bunches• improved measurement of H2 contamination of H-beam• measure beam polarization at injection• measure blue and yellow beam polarization
Eventual goal ofcalibration: ±3%
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
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Forward scattering particle ID ; Forward scattering particle ID ; Correlation of Energy and position Correlation of Energy and position
Strip #1 16
TR M
eV
241AmTOF < +/-8 ns
22 #2sin2 chmR
mT ppR ⇒≈ ϑ
TOF vs TR Si detector of 16channels
#1
#16
#4
TR
TO
F
analysis
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H
+1
0
-1
+1/2 - 1/2
- 1/2 +1/2
mI
P
€
B ∝ r2
r F r = ±k
r r
The Polarized Target - Principle
H2 r
acceptance angle
rH
H2
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H
The Polarized Target - Principle
H2 r
acceptance angle
rH
H2
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• Sextupoles: rare-earth permanent magnets (gradient up to 6 T/cm)• Magnet geometry: 2 magnet groups reduce chromatic aberrations• magnet gaps reduce gas attenuation• taper increases acceptance• RF transitions of high efficiency• very uniform guide field to avoid bunch field depolarization• Field shaping for adiabatic transport
responsible for design: T. Wise UW
H-Jet Design Features
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
permanent magnet sextupole pole tip field 1.5T
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24 sectors separatingmagnets with 1.5 T field at the pole tips.
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
H-jet sextupole separation magnet system.
0 0.5m 1m 1.5m
p-beam
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+1
0
-1
+1/2 - 1/2
- 1/2 +1/2
mI
P
€
B ∝ r2
r F r = ±k
r r
The Polarized Target - Principle
rH
H2
acceptance angle
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rH
H2 H
+1
0
-1
+1/2 - 1/2
- 1/2 +1/2
mI
P
€
B ∝ r2
r F r = ±k
r r
The Polarized Target - Principle
H2 r
acceptance angle acceptance angle
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• Sextupoles: rare-earth permanent magnets (gradient up to 6 T/cm)• Magnet geometry: 2 magnet groups reduce chromatic aberrations• magnet gaps reduce gas attenuation• taper increases acceptance• RF transitions of high efficiency• very uniform guide field to avoid bunch field depolarization• Field shaping for adiabatic transport
responsible for design: T. Wise UW
H-Jet Design Features
APS-DNP W. Haeberli, University of Wisconsin Chicago October 29, 2004
permanent magnet sextupole pole tip field 1.5T