October 9, 2008 | Andro Kacharava (JCHP/IKP, FZ-Jülich)

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Physics Program at COSY-Jülichwith Polarized Hadronic ProbesForschungszentrum Jülich

COSY (Cooler Synchrotron) at Jülich (Germany)

• Hadronic probes: protons, deuterons• Polarization: beams & targets

Overview

• Introduction

• Polarized Hadrons

• COSY–Hardware

• COSY–Research

• Future Plans at COSY

• New Projects

• Summary

⇒ Experimental program with

polarized hadronic probes & strong theory support

Evolution of our view of the nucleon

Hadron Physics: Understanding of all matter comprised of quarks and gluons:

How does Nature make hadrons?

Hadron Physics: Why Spin ?

• Fundamental degree of freedom

• Crucial role in determining the basic structure of fundamental interactions

Spin-dependent decays and scattering:

⇒ Powerful test of theory

⇒ Unique opportunity to probe the inner

composite systems (e.g. proton)

Characteristics:

• Energy range:

0.045 – 2.8 GeV (p)

0.023 – 2.3 GeV (d)

• Max. momentum ~ 3.7 GeV/c

• Energy variation (ramping mode)

• Electron and Stochastic cooling

• Internal and external beams

• High polarization (p,d)

• Spin manipulation

COSY Facility

10 m

Polarized Hadrons at COSY

• Beams:protons (p), deuterons (d) ⇔ Polarized colliding-beams source:

COSY ABS+cesium beam source+ Lamb-shift polarimeter

• Targets:Hydrogen, Deuterium ⇔ Polarized Internal Target (PIT):

ANKE ABS + Storage Cell (SC),EDDA ABS, HERMES ABS

• Reaction products: N ⇔ Self analysing (Λ, Σ decay)

Polarimetry: ⇔ Low-Energy Polarimeter (LEP)Lamb-shift Polarimeter (LSP)Breit-Rabi Polarimeter (BRP)

→

→ →

talks: by R. Engels and A. Nass (session on Oct. 7)

Main components of PIT:• Atomic Beam Source (ABS)

• H or D• H beam intensity (2 HFS)

8 · 1016 atoms/s• Beam size at the IP

σ = 2.85 ± 0.42 mm• Polarization for Hydrogen

PZ = 0.89 ± 0.01PZ = -0.96 ± 0.01

• Lamb-Shift Polarimeter (LSP)• Storage Cell (SC) in target chamber

COSY-Hardware (I): Polarized Internal Gas Target

talk by R. Engels (session on Oct. 10)

ANKE and TOF: no photon detection

ANKE

TOF

ANKE (double polarization):

- Magnetic spectrometer (3 dipoles)

- Internal beam

- (Un-), polarized target (PIT)

TOF (beam polarization):

- Non-magnetic (t-o-f) spectrometer

- Extracted beam

- Large acceptance

- Un- (polarized) cryo-targets

COSY- Hardware (III): Detectors

Relocation from CELSIUS to COSY in 2005

WASA (beam polarization):

- Internal beam

- Electromagnetic calorimeter

- SC solenoid

- Inner and forward tracking

- Pellet target (unpolarized)

Charged particle and

photon detectionWASA

COSY- Hardware (III): Detectors

Commissioning in 2006 – operational from 2007 on

WASA (beam polarization):

- Internal beam

- Electromagnetic calorimeter

- SC solenoid

- Inner and forward tracking

- Pellet target (unpolarized)

Charged particle and

photon detectionWASA-at-COSY

COSY- Hardware (III): Detectors

COSY- Research (I): An Overview

Nuclear Forces Hadronic Spectroscopy (N*´s, Exotics)

Strangeness Role of s-Quark (OZI)

Symmetries Symmetries and Symmetry Breaking(ChS, P, C, IS)

In-mediumModifications Final State Interactions (Bound States)

…

isospin and polarization (beams, targets) as tools

(final state) photons as a probe (WASA)

Spectroscopy, Spin, Symmetry

Topics:

• NN-scattering

• Deuteron break-up

• Pion production

• η-3He interaction (FSI)

• Hyperon-Nucleon interaction

• Symmetry breaking

COSY- Research (II): Selected Recent Results

(1) NN – Interaction

• Ramping mode (Ep < 2.5 GeV)

• Wide energy & angular range

• High precision, consistency

for pp (I=1)-system:

dσ/dΩ PRL 78 (1997); EPJ A 22 (2004)

AN PRL 85 (2000); EPJ A 23 (2005)

A** PRL 90 (2003); PR C 71 (2005)

Full characterization of

elastic pp scattering (PWA)

No dibaryon signal

NN – Interaction (I): The EDDA Legacy

dp observables: dσ/dΩ, T20, T22, Cy,y,

np observables: Ay, Ayy, Dyy, Cxy,y,

quasi-free

dp→ppS (00)+n→→

pd→ppS(1800)+n→→

↓ p

n

d→ ↑ n

↑ p

↑ psp

p→Ddeuteron beam:deuteron target:

• d beam: Tn up to 1.1 GeV for np• d target: Tp up to 2.8 GeV for pn

NN – Interaction (II): np System at ANKE

Epp < 3 MeV

np system: different isospin channel

via Charge-Exchange duteron breakup:

dp→(pp)1S0 n→

22222220 ,,,, εδβγσ +⇒⇒⇒⇒TT

dqd

Axx (T22)

Td = 1170 MeV

Transition from deuteron to (pp)1S0:

pn → np spin flip

np spin-dependent amplitudes:

Results:• Method works at Tn = 585 MeV• Application to higher energies• Td=2.23 GeV (in progress)

D.Chiladze et al. PLB 637, 170 (2006)

Ayy (T20)

NN – Interaction (III): np Results at ANKE

Tn = 585 MeV⇒⇒⇒⇒ SAID np amplitudes

New !

dp→(pp)1S0 n→

22222220 ,,,, εδβγσ +⇒⇒⇒⇒TT

dqd

Axx (T22)

Td = 1170 MeV

Transition from deuteron to (pp)1S0:

pn → np spin flip

np spin-dependent amplitudes:

Results:• Method works at Tn = 585 MeV• Application to higher energies• Td=2.23 GeV (in progress)

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

=> relative phases

Cy,y

Cx,x

D.Chiladze et al. PLB 637, 170 (2006)

Ayy (T20)

dp→→

NN – Interaction (IV): np Results at ANKE

(2) Meson Production

COSY: from Pions to the Phi

• Derive chiral three-body forces from p-wave pion production

• Very different kinematics, but same δ : consistency check of ChPT for NN → NNπ

• Model-independent extraction from ANKE data pd → pspppπ-

pd elasticRIKEN, KVI, ...

1S0 → 3S1p

IUCF

(3S1 – 3D1) → 1S0p(unknown)

Role of 4Nπ contact term

→→

δπ

p

δ

p

n

p

π+

p

δ

p

p

n

π-

Meson production (II): Motivation

Ch. Hanhart et al., PRL 85, (2000)

Experiment is scheduled for 2009

Meson production:

pN→ppsX

X=π (ChPT)

X=(2π) (ABC effect), η

X=ω, φ (OZI)

By-product:

Inverse diproton photodisintegration

pp→ppsγγγγ

Same kinematics as np→→→→dγγγγ

M1 multipole is forbidden

Next

Polarization observables (Ay, Ayy, Axx )

Meson production (III): Diproton final state

V.Komarov et al., PRL 101(2008)

PLB 661 (2008); PLB 635 (2006)

• Deuteron: bound (p+n) system, very well studied• Diproton: free pp-pair in 1S0 state, Epp < 3 MeV

New tool to study hadron interactions !

• Precison data, “step function”: 0→ 400 nb w/i 0.5 MeV• Implies large 3Heη scattering length (~ 10 fm)

d+p→3He+η: Total C.S.

η- 3He Interaction (I): (Quasi-) bound state

T. Mersmann et al., PRL 98, 242301 (2007)

quasi- bound state vwithin

< 1MeV of threshold ?

• d+p→ 3He+η:::: Angular distr.

[MeV/c]η momentum pη0 20 40 60 80 100

αas

ymm

etry

fac

tor

-0.3

-0.2

-0.1

-0

0.1

0.2

0.3

0.4

C. Wilkin et al., PLB 654, 92 (2007)

A big phase variation of the s-wave

indication for a quasi-bound state?

w/ phase variation

222

* )Re(2CpfCfp

s

s

ηηα

+=

2 21 26 p

d p p A Bd ησ = +

Ω

2 2

20 2 222

B AT

A B

−=

+

220| | (1 2 )pp dA T

p dη

σ= −Ω

220

1| | (1 )2

pp dB Tp dη

σ= +Ω

22,2

)*Re(2BABAC yy

+= Phase determination

between A and B

η- 3He Interaction (II): (Quasi-) bound state

d+p→ 3He+η: (next step)→ →

d+p→ 3He+η: (analys. in progress)→

GEM: pd → 3Heη

SATURNE: pd → 3Heη

NA48: π− p→ η n

MAMI: γ p → η p

KLOE: φ → η γ

CLEO: Ψ(2s) → η J/ψ

Further investigations at COSY: d+p→3He+η ; ∆m~50 keV(analysis in progress)

→

Precision data – but inconsistency w/ new data !?

η- 3He Interaction (III): η-Meson mass

dBarrier bucket

New technique !

RF solenoid EDDA

RF-induced spin-resonance:

talk by M. Leonova (session on Oct. 10)

PLB 619 (2005) 281

∆p/p ~ 3 · 10-5

0

1 1 resfG f

γ

= ⋅ −

(3) Strangeness DoF

COSY-TOF: decay vertex (2 → 4)

Λ

p p K+ Y N (mostly COSY data)

pp → pK+Λ

pp → pK+Σ0

without FSIwith FSI

Strangeness production (I): YN Interaction

PLB 649 , 252 (2007): PLB 652, 245 (2007)

Importance of Final State Interaction

Incoherent sum of 3S1 and 1S0

FSI with unknown relative strengths

Spin dependence of FSI unknown

ΛN scattering length: singlet (as) and triplet (at) part separately

2626

Spin/isospin dependence

• TOF: high-resolution single polarized

p+p→K+(Λp) at (θK,cm = 90°) ⇒ at

ANKE: double polarized p+n→K+(Λn)(1 – CNN)·σ at (θK,cm = 0°) ⇒ as

Strangeness production (II): YN Interaction

• Poor data base:- ΛN little known - ΣN nothing known

• YN scattering experiments difficult⇒ large uncertainty in Λp scattering length

Theory Model-free determination in production reactions

Method: dispersion relations

Theory precision is 0.3 fm

→

→ →

⇔

A. Gasparyan et al., PRC 69, 034006 (2004)

Future plans: Experiments with polarized probes

2005−2009

2010−2014

COSY proposal #152ArXiv:nucl-ex/0511028

• Isospin violation in d+d→α+π0

Goal: determination of p-wave contributionat Q=60 MeV (Td=350 MeV)

• Pilot measurement: dd →3He+n+π0

(analysis in progress)

→ most severe background channel→ probes the same partial waves

Next step: polarized beam experiment d+d→α+π0

1000παdd 0

→+→+

Future plans: Exploration WASA-at-COSY

Charge Symmetry Breaking(subset of isospin symmetry)(subset of isospin symmetry) E. Stephenson et al., PRL 91, 142302 (2003)

→

Q ≈ 3.0 MeV

New projects: at COSY

• SPIN@COSY:Spin-Manipulating Polarized Deuterons and Protons

⇒ needed to maintain and SPIN-FLIP GeV to TeV stored polarized beams

talk by M. Leonova (session on Oct. 10)

• dEDM: deuteron Electric Dipole Moment

⇒ COSY task: polarimeter database and demonstration of concepts

talk by Y. Semertzidis (session on Oct. 7)

New projects: FAIR at GSI

Floor Plan FAIR-Facility at GSI (Darmstadt), Germany

Existing Facility

New Part:- Atomic Physics- Nuclear Physics (RIB)- Hadron Physics- Nucleus Nucleus Coll.- …

HESR:

Hadron Physics with Anti-Proton

Beams

3131

Method: Spin Filtering ⇒ proton polarization due to multi-pass

interaction with polarized targets (also works for antiprotons)

towards an asymmetric polarized antiproton-proton collider• Depolarization of beams with unpolarized targets (COSY)• Polarization build-up (COSY)• Antiprotons (AD at CERN)

talk by E. Steffens (session on Oct. 8)

talks: by F. Rathmann and

A. Nass (session on Oct. 7)

talk by M. Anselmino (session on Oct. 7)

Physics: Transferse spin structure of the nucleon

New projects: HESR upgrade (Polarized Antiprotons)

COSY - unique opportunities for hadron physics withpolarized hadronic probes (beam & target)

ANKE, TOF, WASA: state-of-the-art, complementary

Physics: “Spectroscopy, Spin, Symmetries” – selected examples and further plans at COSY

Vision from COSY to: FAIR/HESR/PANDA –physics with polarized antiprotons (PAX)

Summary

The END

Thank you very much for your - attention –

Many thanks to the conference organizers !