1. Today’s topics; New AN and ANN results at s = 6.9 GeV
Measurement of the Analyzing Power AN in pp elastic scattering in the CNI region with a Polarized Atomic Hydrogen Gas Jet Target
RUN4 -JET commissioning
(2004 April 26th -May 14th)
H-Jet target pol. ;  0.018!
0.001 < -t < (GeV/c)2
Data taking:
100GeV/c proton beam (s=13.7 GeV)
90hours, 4.3M elastic events
PLB 638 (2006),
24GeV/c proton beam (s=6.9 GeV)
16 hours, 0.8M elastic events
Today’s topics; New AN and ANN results at s = 6.9 GeV
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

2. Forward scattered proton
Transverse spin dependent asymmetries of pp elastic scattering as a function of -t
Forward scattered proton
Single spin asymmetry
Double spin asymmetry
proton beam
proton target
Recoil proton

3. 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
spin non–flip
double spin flip
single spin flip
UA6 (CERN) s=24.3 GeV
<++M++> ?
pout1
pin1
pin2
pout2 +
Total cross-section
Differential cross-section

4. Missing pieces of helicity amplitudes: 2had and 5had
spin non–flip
double spin flip
single spin flip
Well known
Unknown
Very small
Single spin asymmetry
Double spin asymmetry
If hadronic spin-flip amplitudes are small, ANN is small!

5. Measurements of AN & ANN in the CNI region @ s=13.7 GeV
PLB 638 (2006),
Set r5 as free parameter:
 2/ndf = 11.1/12
 Im r5 = 0.015  0.029
 Re r5 =  
 |r5| is consistent with zero!
|r5| =0
Compare measured AN and expected curve with |r5| =0  2/ndf = 13.4/14, |r5| is consistent with zero!
2had and 5had are consistent with zero at s = 13.7 GeV.
Measured ANN at s = 13.7 GeV are consistent with zero!  <ANN> =  

6. s dependence of 2had, 5had ?
Today’s topics; New AN and ANN results at s = 6.9 GeV
s dependence of 2had, 5had ?

7. JET target Polarized Atomic Hydrogen Gas Jet Target System
Si 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
JET target
FWHM ~6.5mm
RHIC 24, 100GeV/c proton beam ~1mm
Recoil particle
left
80cm
Si detectors
JET
right

8. Elastic event selection and –t measurement
R big  TR big  fast protons
proton beam
Forward scattered proton
proton target
recoil proton  measure! R
ch#1
#16
Channel # corresponds to recoil angle R.
Every channel measures TR & ToF of recoil particles.
2 correlations (TR & ToF ) and (TR & R )  Elastic event selection

9. AN and r5 results at s= 6.9 GeV
0.8 M pp elastic events.
Errors on the data points are statistics only.
Components of systematic errors
Acceptance asymmetry
Background correction
Elastic event selection
Set r5 as free parameter
 Im r5 = 0.152  0.014
 Re r5 = 0.045  0.038
2/ndf = 2.87/7
preliminary
|r5|=0
r5 is not zero at s=6.9 GeV ! 2/ndf = 35.5/9
r5 has s dependence ?  Not improbable; theoretical prediction using 100GeV/c and

10. AN collection in the CNI region
Pbeam=24 GeV/c
Pbeam=100 GeV/c
ANpp
|r5|=0
|r5|=0
preliminary
Theoretical interpretation is undergoing!
Next inputs: RUN6 s = 7.6 GeV data ~1 week (31 GeV/c beam)
Pbeam=21.7 GeV/c J. Tojo et al.
Pbeam=100 GeV/c O. Jinnouchi et al.
ANpC
|r5|=0
|r5|=0
preliminary

11. 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
preliminary
Mean value for all –t range:
<ANN> =  at s = 6.9 GeV
 Consistent with <ANN> =  at s = 13.7 GeV

12. Summary r5 has s dependence
We measured AN and ANN by use of the polarized hydrogen gas jet target and RHIC polarized proton beam
0.001 < -t < (GeV/c)2
Target polarization ;  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.
ANN data are consistent with zero
<ANN> =  at s = 13.7 GeV
<ANN> =  at s = 6.9 GeV
r5 has s dependence

13. Theoretical prediction of 24GeV/c AN
From Larry Trueman (BNL)
24GeV/c, 100GeV/c  Pomeron
100GeV/c  , 
Next inputs: RUN6 s = 7.6 GeV data ~1 week (31 GeV/c beam)

14. Theoretical interpretation is undergoing!pp
100 GeV/c
24 GeV/c pC
21.7 GeV/c
Theoretical interpretation is undergoing!
Next inputs: RUN6 s = 7.6 GeV data ~1 week (31 GeV/c beam)

15. Helicity amplitudes pC elastic scattering and r5 pC
Analogy to pp helicity amplitude formalism
pC process being described by two amplitudes
Non-flip
Spin flip
Phys. Rev. D64,