Deuteron Polarimetry at COSY

David ChiladzeIHEPI, Tbilisi State University

IKP, Forschungszentrum Jülich

2.10.2006 SPIN 2006 2

Outline

Introduction

Experimental tools

Beam polarimetry

Summary & outlook

2.10.2006 SPIN 2006 3

Introduction: NN Scattering

Characterization requires precise data

for Phase Shift Analyses

Current experimental status of NN

data:

pp system (I=1) well-known up to 2.5

GeV (EDDA): Majority of data on

unpolarized, single, and double

polarized observables

np system (I=0) poorly known →

ANKE will provide high-quality data in

forward/backward region Ayy

d/d

np forward

np charge-exchange

np forward

np charge-exchange

ANKErange

ANKErange

2.10.2006 SPIN 2006 4

Introduction: Motivation

Double polarized experiments at ANKE

np spin physics

Single polarized experiment

Polarized charge-exchange reaction dp→(2p)n

Direct reconstruction of the spin-dependent np amplitudes

via measurement of and T20 & T22 (Tn = 0.6 – 1.15 GeV)

Aim of first measurement (Td = 1.2 GeV)

Feasibility of the experiment

Polarimetry standards at ANKE

→

dt

d

(Proposal #152, “Spin physics from COSY to FAIR”)

2.10.2006 SPIN 2006 5

Experimental tools: COSY

Polarized and unpolarized

proton and deuteron source

Protons up to 2.88 GeV

Deuterons up to 2.23 GeV

Internal and external

experiments

ANKEANKE

EDDAEDDA

LEPLEP

2.10.2006 SPIN 2006 6

L E P

E D D A

Experimental tools: LEP & EDDA

dp → dp

Td = 270 MeV

Ay, Ayy (65° – 95°)c.m.

dC → dC

Td = 75.6 MeV

Ay(40°) = 0.61 ± 0.04S.Kato et al.

Nucl.Inst.Meth. A 238, 453 (1985)

E.J. Stephenson

Deuteron Polarimeter for EDM Search.

K. Sekiguchi et al.

Phys.Rev. C 65, 034003 (2002)

→

→Spinmode

Pz ideal Pzz idealIntensity[I0]

0 0 0 11 -2/3 0 12 +1/3 +1 13 -1/3 -1 14 +1/2 -1/2 2/35 -1 +1 2/36 +1 +1 2/37 -1/2 -1/2 2/3

Pz ≈ 75 % Pzz ≈ 60 %

Slope = 1.05 ± 0.06Offset = 0.04 ± 0.01

2.10.2006 SPIN 2006 7

Experimental tools: ANKE setup

Td = 1170 MeV

dp → dp

dp → 3Heπ0

dp → dpsp π0

dp → (pp)n

→

→

→

→

2.10.2006 SPIN 2006 8

Beam polarimetry: Reaction identification

Low branch High branch

dp → dp

dp → dpsp π0 dp → (pp)n

dp → 3Heπ0

mπ0

2.10.2006 SPIN 2006 9

SAID

ANKE

Beam polarimetry: Ay, Ayy measurement

(Tn = 585 MeV)

dp → dp

dp → 3Heπ0

np → dπ0

dp → (pp)n

D. Chiladze et al. Phys. Rev. STAB 9, 050101 (2006) Depolarization less then 4%

ANKEANKE

ANKE

2.10.2006 SPIN 2006 10

Beam polarimetry: CE reaction

dp→(pp)1S0 n

→

2222

2220 ,,,, TTdqd

Axx (T22)

Ayy (T20)

Td = 1170 MeV

Transition from deuteron to (pp)1S0:

pn np spin flip

Obtain np elementary spin-dependent amplitudes:

Results: Method works at Tn = 585 MeV Application to “uncharted territory”

Next step: Double polarized → Cy,y, Cx,x

(using PIT see talk K. Grigoriev)

Cy,y

Cx,x

D.Chiladze et al. Phys. Let. B 637, 170 (2006)

2.10.2006 SPIN 2006 11

Beam polarimetry: Polarization export

ResultsResults

y I = -0.213 ± 0.005

y III = -0.216 ± 0.006

yy I = 0.057 ± 0.003

yy III = 0.059 ± 0.003

Polarized deuteron beam at 3 energies

Calibration of the beam polarization of arbitrary energy

Super cycle: Td = 1.2 GeV, 1.8 GeV.

Time

II

I III

1.2 GeV 1.2 GeV

1.8 GeV

Energy rampingEnergy ramping y I = y III

yy I = yy III

2.10.2006 SPIN 2006 12

Summary & Outlook

Polarisation standard at 1.2 GeV

Analysing power measurement

Polarisation export technique

Higher beam energy (up to 2.3 GeV)

Double polarized dp→(2p)n reaction→→

2.10.2006 SPIN 2006 13

LEP (Td = 76 MeV) dC → dC

EDDA (Td = 270 MeV) dp → dp

ANKE (Td = 1170 MeV) dp → dp dp → 3Heπ0

dp → dpsp π0

dp → (pp)n

RL

RL

yz NN

NN

A

1

3

2P

PzEDDA = (0.95±0.02)Pz

LEP + (0.04±0.01)

2.10.2006 SPIN 2006 14

Experimental facility

LEP (Td = 76 MeV)

EDDA (Td = 270 MeV)

ANKE (Td = 1170

MeV)

ANKEANKE

EDDAEDDA

LEPLEP

Spinmode

Pz ideal Pzz idealIntensity[I0]

0 0 0 11 -2/3 0 12 +1/3 +1 13 -1/3 -1 14 +1/2 -1/2 2/35 -1 +1 2/36 +1 +1 2/37 -1/2 -1/2 2/3

2.10.2006 SPIN 2006 15

Introduction: np elastic (small angle)

d→

↑ n

↑ p

↑ psp

p

p→

D

dp observables: d/d, T20, T22, Ay,y, ...

np observables: Ay, Ayy

d beam: up to 1.1 GeV for npd target: up to 2.8 GeV for pn

quasi-free

pd→psp (pn)→ →dp→psp (np)→→

np forward

deuteron beam:

deuteron target:

n

2.10.2006 SPIN 2006 16

Introduction: np elastic (large angle)

↓ p

n

dp observables: d/d, T20, T22, Ay,y, ...

np observables: Ay, Ayy, Dyy, Axy,y, ...

quasi-free

dp→(pp)1S0n

→→

pd→(pp)1S0n→→

d→

↑ n

↑ p

↑ psp

p→

D

np charge-exchange

deuteron beam:

deuteron target:

d beam: up to 1.1 GeV for npd target: up to 2.8 GeV for pn