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