Spin Physics of NN Interactions at COSY Andro Kacharava Universität Erlangen

Andro Kacharava Spin Physics at COSY 1

Spin Physics of NN Interactions

at COSY

Andro Kacharava Universität Erlangen

16th SPIN Symposium, Trieste, October 10_16, 2004

Spin Physics at COSY 2

Outline

• Experiments at COSY

• NN Interaction

• Selected Results

• NN Elastic

• Meson Production

• YN Interaction

• New Equipment

• Conclusion


Experiments: COSY Accelerator

COoler SYnchrotron:

Ions: (pol. + unpol.) p and d

Momentum: 300 to 3700 MeV/c

... unique possibilities:

- Spin Manipulation

- Electron Cooling at Injection

- Stochastic Cooling >1.5 GeV/c

Targets:

- Internal: Solid, Cluster,

Polarized Atomic

- External: Solid, Liquid


Cooler Synchrotron (COSY) & Detector systems

COSY

ANKE

EDDA

Experiments: Current Facilities

TOF

COSY-11


NN Interaction

• Fundamental for strong interaction.

• Characterization requires precise data for PSA.

• pp system: up to 2.5 GeV well-known (…, PINTEX, EDDA).

• np system: ANKE-COSY will provide high-quality data.

• Current experimental status:

R.Arndt: Gross misconception within the community that

np amplitudes are known to a couple of GeV.

J.Bystricky: Measurements of ANY observables at small

angle are highly desirable to improve PSAs.


NN Interaction: Observables

N = yS = xL = z

dσ/d = I0 ·[1+AN·(PN+QN)

+ ANN·PN·QN

+ ASS·PS·QS

+ ASL (PL·QS+PS·QL)

+ ALL·PL·QL]

AN and Aik sensitive only

to spins in initial state: easily accessable

Storage rings - unique environment for double-polarized experiments.


Selected Results: pp elastic at EDDA

Characterization of NN-interaction

•Large kinematical range: 1.0-3.3 GeV/c, 30°-90° [c.m.]

•High precision data- Unpolarized, single, double polarized.- Large impact on pp PSA >500 MeV.

•Further Results:•No Evidence for dibaryons•Polarimetry for the pp system

T=2.1 GeV

F. Bauer et al., PRL 90 (2003)



COSY

ANKE

Experiment: EDDA

TOF

COSY-11EDDA


Selected Results: pp elastic at EDDA

Characterization of NN-interaction

•Large kinematical range: 1.0-3.3 GeV/c, 30°-90° [c.m.]

•High precision data- Unpolarized, single, double polarized.- Large impact on pp PSA >500 MeV.

•Further Results:•No Evidence for dibaryons•Polarimetry for the pp system

T=2.1 GeV

F. Bauer et al., PRL 90 (2003)


Selected Results: NN Modeling above 1 GeV

> 1 GeV: Modified model

original + optical potential + Reggezied vector meson

Total

Elastic

Modified model

Original model R.Machleidt (workshop in Tbilisi, Sep’04)

< 1 GeV: Original model – OBE + Δ


Selected Results: NN Modeling above 1 GeV

R. Machleidt & EDDA data (arXiv:nucl-th/0311002,2003)

PSA (VPI)originalmodified


Selected Results: Status of NN models >1 GeV

• SATURNE and EDDA: Transition region (few GeV). • NN model for transition region:

- σ reproduced, Spin observables > 1 GeV wrong!- Between 1 and 10 GeV serious problems!

R.Machleidt: Defeat of Theory, Triumph of Experiment.We need new ideas !


Selected Results: np elastic at ANKE

• Spin structure of np→pn reaction amplitudes

• Method: Spin filter

• Next Step: Measurement of spin observables for pn system up to 3 GeV

• Method: Spectator technique

→ →pd→psp (pn)

dp→(pp)1S0 n

→→



COSY

EDDA

Experiment: ANKE

TOF

COSY-11

ANKE


Selected Results: np elastic at ANKE

• Spin structure of np→pn reaction amplitudes

• Method: Spin filter

• Next Step: Measurement of spin observables for pn system up to 3 GeV

• Method: Spectator technique

→ →pd→psp (pn)

dp→(pp)1S0 n

→→


NN Interaction: np Amplitudes

In collinearkinematics

over a range in t

;2/,31 2

3

4

qkSIkdtd

d qkS 2,

;

qkSR

2,

2[ ] ;21 22222

20 RIT ;23 2222

22 RIT

R.IC zz *, 2 IC xx *, ;2 RIC yy *, ;2

2222

2220 ,,,, TTdtd

,2;222

20

22 ITI

cos3;2 *,

*, yxzyy ICIC

dp→(pp)1S0 n

→

,RδεβΙ 2222 2


Selected Results: Test measurement of CE

Spin ModeTheoretical maximum

Intensity[I]Pz Pzz

0 0 0 1

1 -2/3 0 1

2 +1/3 +1 1

3 -1/3 -1 1

4 +1/2 -1/2 2/3

5 -1 +1 2/3

6 +1 +1 2/3

7 -1 -1/2 2/3

COSY Deuteron Beam I = 3 109 fr Acceptance


Selected Results: dp Reactions

• dp elastic• dp→3He0

• dp→pspd0

• Polarimetry, Luminosity

dp→(pp)n


Selected Results: Spin dependent amplitudes

)(79.10

0

)(15.086.10

0

SAID

ANKE

22

22

20002

002

T

APTDSG 142(0)

DTAPTDSG 2142 (0)

DSG, DT, APT from SAID

27.0

Value from SAID WI00Error from R. Arndt SE-Solution

T20 = 0.39 ± 0.04 (ANKE)

dp→(pp)1S0 n

→

Method W

orks !

!!

Method W

orks !

!!Bugg, Wilkin, NP A467(1987) 575


Selected Results: NN program at ANKE

Future polarized ANKE Experiments:

1. Charge-Exchange breakup

2. np Elastic scattering

3. Deuteron breakup

dp→(pp)1S0 n

→ →

pd→psp(pn)→ →

pd →(pp)1S0 n

→ →

Strategy: Begin commissioning of PIT using high rate reactions that can be easily identified (e.g. CE).

Talk S. Yaschenko


Selected Results: Meson Production

•η production at COSY-11

pp→ppη near threshold

Single Polarization: Ay

distinguish different models...... dominant ρ exchange___ π and η exchange

Double Polarization: Cxx (Cyy)

model independent extractionof amplitudes:

→

P. Winter et al., PLB, 544 (2002)

dashed: 1S0s final state

dash-dotted: 1S0s + 3P0

s

dotted: 1S0s +

3P0s+3P2

s

K. Nakayama et al., PRC, 68 (2003)



COSY

ANKE

EDDA


TOF

COSY-11


Selected Results: Meson Production

•η production at COSY-11

pp→ppη near threshold

Single Polarization: Ay

distinguish different models...... dominant ρ exchange___ π and η exchange

Double Polarization: Cxx (Cyy)

model independent extractionof amplitudes:

→

P. Winter et al., PLB, 544 (2002)

dashed: 1S0s final state

dash-dotted: 1S0s + 3P0

s

dotted: 1S0s +

3P0s+3P2

s

K. Nakayama et al., PRC, 68 (2003)


Selected Results: YN Interaction

• Strangeness production at COSY-11

• Comparison of Λ - and Σ0 – production via pp p K+Λ/Σ0 close to threshold

• Parameterisation includes:• Individual Λ and Σ0 excitation

functions• p-Y final state interactions

• Hyperon production in pp pK+:• Production mechanism• Next: Double polarization

spin-dependence of p (ANKE, TOF)


New Equipment : WASA@COSY

• Symmetry and –breaking (ISB, …)

• Hadronic states spectroscopy (, …)

• Baryon-baryon interaction (np, YN)

• Hadronic medium effects (Kaon mass)


New Equipment: PIT & Spectator Telescope

PIT: Polarized Internal Target::- ABS

- Lamb-Shift Polarimeter

- Storage Cell

Spectator: Silicon telescope array

Talk K. Grigoriev, Sec 8, Oct’15

beam


New Equipment: Polarized Target for TOF

PT @ COSY-TOF

(H. Dutz et al.,)

PS185/3 @ LEAR set-up Target material test by

Bochum PT-group Components installation

Bonn PT-lab Test of complete system in

spring 2005 Installation at TOF

Status and Outlook



COSY

ANKE

EDDA


COSY-11

TOF


New Equipment: Polarized Target for TOF

PT @ COSY-TOF

(H. Dutz et al.,)

PS185/3 @ LEAR set-up Target material test by

Bochum PT-group Components installation

Bonn PT-lab Test of complete system in

spring 2005 Installation at TOF

Status and Outlook


Future Experiments: Parity of θ+ (1540)

COSY is perfectly suited to determine the parity free of any model!

Spin-correlation coefficient Axx in pp θ++

+1

-1

50 Q [MeV]0

neg. Parity

pos. ParityA

xx

PLB,590

,(2004),

39-44

Talk Y. Uzikov, Sec 4, Oct’14


Existing Facilities ANKE, EDDA, COSY11 and TOF

pursue a strong spin physics program

Conclusion

Single and Double Polarization Experiments•NN Interaction (pn)•YN Interaction•pd Dynamics•Meson Production in pp and pn Collisions•Parity of Θ+ Pentaquark


Observables: np SAID data

APT (KLL) 600 MeV

APT (KLL) 800 MeV

APT (KLL) 900 MeV

DT (KNN) 600 MeV

DT (KNN) 800 MeV

DT (KNN) 800 MeV

DSG 900 MeV

DSG 800 MeV

DSG 600 MeV


np SAID data: Error analysis


New Equipment: Spectator Detector

Features:– Three layers (double sided)

1st: 60 m2nd: 300 m3rd: 5 mm

– Ekin~2 MeV (60 MeV/c)

– 800 Channels– Self-triggering– On-board electronics

– UHV compatible– Large Acceptance

• 10% per telescope• 30 mm from the beam


New Equipment: Polarized Internal Target

• Development for ANKE Atomic BeamSource

Lamb-Shift Polarimeter

Atomic Beam Intensity

7.4·1016 atoms/s (2 HFS)

Lyman- Spectrum

Talk K. Grigoriev, Sec 8, Oct’15


Luminosity of ANKE PIT

ANKE Luminosity (double polarized)Target density: (2.5 – 7.1)·1013 cm-2

Beam intensity: 5·109 particlesLuminosity: (2.0 - 5.7)·1029 cm-2s-1

L

dbeam

I

ddt t ~ I~ ILL22dd-3-3TT--

½½

Storage cell target requires a small -function at the interaction point: beam~β½

I=7.51016 H/s

T=300 KL=350 mma=15 mmb=20 mm

dt =2.5·1013 cm-2

a=10 mmb=12 mmdt =7.1·1013 cm-2

Documents

Spin Physics of NN Interactions at COSY Andro Kacharava Universität Erlangen