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Measurement of the Analyzing Power A N in pp elastic scattering in the CNI region with a Polarized Atomic Hydrogen Gas Jet Target. RUN4 -JET commissioning (2004 April 26 th -May 14 th ) H-Jet target pol. ; 0.924 0.018! 0.001 < -t < 0.032 (GeV/ c ) 2 Data taking: - PowerPoint PPT Presentation
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Measurement of the Analyzing Power AN in pp elastic scattering in the CNI region with a Polarized Atomic
Hydrogen Gas Jet Target
Today’s topics; New AN and ANN results at s = 6.9 GeV
RUN4RUN4 -JET commissioning
(2004 April 26th -May 14th)
H-Jet target pol. ; 0.924 0.018!
0.001 < -t < 0.032 (GeV/c)2
Data taking:
• 100GeV/c proton beam (s=13.7 GeV)
• 90hours, 4.3M elastic events
• PLB 638 (2006), 450-454
• 24GeV/24GeV/cc proton beam ( proton beam (s=6.9 GeV)s=6.9 GeV)
• 16 hours, 0.8M elastic events16 hours, 0.8M elastic events
Hiromi Okada from RIKEN
I. Alekseev, A. Bravar, G. Bunce, S. Dhawan, O. Eyser, R. Gill, W. Haeberli,
O. Jinnouchi, A. Khodinov,K. Kurita, Z. Li, Y. Makdisi,
I. Nakagawa, A. Nass, S. Rescia, N. Saito, H. Spinka, E. Stephenson, D. Svirida,
T. Wise, A. Zelenski
Single spin asymmetry
Double spin asymmetry
NNbeamN
N
etargt
NN
A
P
1tA
Transverse spin dependent asymmetries of pp elastic scattering as a function of -t
0P , P
0P , P
A
targetbeam
beamN
beametargt
etargtN
N
t
%5P
P ,
AP
beam
beam
N
beamN
beam
Forward scattered proton
proton target
Recoil proton
02 inout ppt
proton beam
%5A
A
N
N
pp elastic scattering in the CNI region Described using Helicity Amplitudes 1~ 5
Interaction matrix M; Nuclear + Coulomb force Nuclear and Coulomb forces become similar in size at –t~10-3 (GeV/c)2. They interfere with each other Coulomb Nuclear Interference
|M|t,s
|M|t,s
|M|t,s
|M|t,s
|M|t,s
5
4
3
2
1 spin non–flip
double spin flip
spin non–flip
double spin flipsingle spin flip
Differential cross-section
22
|t,s|s
4
dt
d
231
UA6 (CERN) s=24.3 GeV
Ciemi
hadii e
Total cross-section
0,sIms
8tot
<++M++>?
pout1
pin1
pin2pout
2++
++
Missing pieces of helicity amplitudes: 2had and 5
had
|M|t,s
|M|t,s
|M|t,s
|M|t,s
|M|t,s
5
4
3
2
1 spin non–flip
double spin flip
spin non–flip
double spin flipsingle spin flip
Single spin asymmetry
Double spin asymmetry
2em*had5
had*em5N ImA
2had2
*2had5NN Re 2 A
Very small
Well known
Well known
UnknownUnknown
UnknownUnknown
?, had2
had5 If hadronic spin-flip amplitudes
are small, ANN is small!
• Compare measured AN and expected curve with |r5| =0 2/ndf = 13.4/14, |r5| is consistent with zero! 22
hadhad and and 55hadhad are coare co
nsistent with zero at nsistent with zero at s = 13.7 GeV.s = 13.7 GeV.
s=13.7 GeVPLB 638 (2006), 450-454
had
had5p
5Imt
mr
Set r5 as free parameter:
2/ndf = 11.1/12
Im r5 = 0.015 0.029
Re r5 = 0.0008 0.0091
|r5| is consistent with zero!
Measurements of AN & ANN in the CNI region @ s=13.7 GeV
|r5| =0
2em*had5
had*em5N ImA
• Measured ANN at s = 13.7 GeV are consistent with zero! <ANN> = 0.0024 0.0015
Today’s topics; New AN and ANN results at s = 6.9 GeV
s dependence of 2had, 5
had ?
GeV 9.6sat 25.0
GeV 7.13sat 08.0
0,sIm
0,sRes
GeV 7.13s
GeV 9.6s
2em*had5
had*em5N ImA
right
JET target
RHIC 24, 100GeV/c proton beam ~1mm
Recoil particle
FWHM ~6.5mm
left80cm
Si detectors
JET
Polarized Atomic Hydrogen Gas Jet Target SystemSi detectors (8cm * 5cm)*3* L-R sides
Strip runs vertical with beam
1ch width = 4mm (400strips)
Channel # corresponds to recoil angle
Each channel measures Energy and TOF
Recoil particle
8cm
5cm
Elastic event selection and –t measurement
proton beam
Forward scattered proton
proton target recoil proton recoil proton
measure! measure!
• Channel # corresponds to recoil angle R.• Every channel measures TR & ToF of recoil particle
s.• 2 correlations (TR & ToF ) and (TR & R ) Elastic event selection
R#ch
R big TR big fast protons
#16R
ch#1
R
p
T2
mLToF_cal
2RpR sinm2T
0 RpT2mt-
AN and r5 results at s= 6.9 GeV
r5 is not zero at s=6.9 GeV ! 2/ndf = 35.5/9
r5 has s dependence ? Not improbable; theoretical prediction using AN
pC @24GeV/c, 100GeV/c and AN @100GeV/c.
1.1. 0.8 M pp0.8 M pp elastic events.elastic events.
2.2. Errors on the data points are statiErrors on the data points are statistics only.stics only.
3.3. Components of systematic errorsComponents of systematic errors
• Acceptance asymmetry Acceptance asymmetry
• Background correctionBackground correction
• Elastic event selectionElastic event selection
4.4. Set rSet r55 as free parameter as free parameter
Im r5 = Im r5 = 0.152 0.152 0.014 0.014 Re r5 = Re r5 = 0.045 0.045 0.038 0.038 22/ndf = 2.87/7/ndf = 2.87/7
preliminary
|r5|=0
had
had5p
5Imt
mr
ANpC
Pbeam=100 GeV/c O. Jinnouchi et al.
|r5|=0 |r5|=0
Pbeam=21.7 GeV/c J. Tojo et al.
ANpp
Pbeam=100 GeV/cPbeam=24 GeV/c
|r5|=0 |r5|=0
Next inputs: RUN6 Next inputs: RUN6 s = 7.6 GeV data ~1 week (31 GeV/s = 7.6 GeV data ~1 week (31 GeV/c c beam) beam)
Theoretical interpretation is undergoing!Theoretical interpretation is undergoing!
AN collection in the CNI region
preliminary
preliminary
0 ,
Im
ImA
Re 2 A
had
had2
NN
2had2
*2had5NN
t-
ANN results at s=6.9 and 13.7 GeV • Errors on the data points are
statistics only
• Components of systematic errors
• Relative luminosity of RHIC-beam and H-jet-target
• Polarization of RHIC-beam
• Background correction
• Event selection
Mean value for all –t range:<ANN> = -0.0056 0.0036 at s = 6.9 GeV Consistent with <A<ANNNN> = -0.0024 > = -0.0024 0.0015 0.0015 at s = 13.7 GeV
preliminary
Summary• We measured AN and ANN by use of the polarized hydrogen gas jet target and
RHIC polarized proton beam – 0.001 < -t < 0.032 (GeV/c)2
– Target polarization ; 0.924 0.018 s=13.7 GeV, 4.3M elastic events (90hours) : RHIC 100GeV/c beam s=6.9 GeV, 0.8M elastic events (16hours) : RHIC 24GeV/c beam
• We compared AN with no hadronic spin-flip 2/ndf = 13.4/14 at s = 13.7 GeV. 2/ndf = 35.5/9 at s = 6.9 GeV.
• Extracted r5 from AN data– r5 at s = 13.7 GeV is consistent with zero.– r5 at s = 6.9 GeV is not zero.
• AANNNN data are consistent with zero– <A<ANNNN> = -0.0024 > = -0.0024 0.0015 0.0015 at s = 13.7 GeV – <ANN> = -0.0056 0.0036 at s = 6.9 GeV
had
had5p
5Imt
mr
r5 has s dependence
ANpC @ 24GeV/c, 100GeV/c Pomeron
AN @ 100GeV/c ,
Theoretical prediction of 24GeV/c AN
Next inputs: RUN6 s = 7.6 GeV data ~1 week (31 GeV/c beam)
From Larry Trueman (BNL)
Next inputs: RUN6 s = 7.6 GeV data ~1 week (31 GeV/c beam)
Theoretical interpretation is undergoing!
pC21.7 GeV/c
pp100 GeV/c
24 GeV/c
Helicity amplitudes Helicity amplitudes pCpC elastic sca elastic scattering andttering and rr55
pCpC
Non-flipNon-flip
Spin flipSpin flip
Analogy to pp helicity amplitude formalismpC process being described by two amplitudes
Phys. Rev. D64, 034004