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breit edda
Mitglied der Helmholtz-Gemeinschaft
Physics Program at COSY-Jülich
with Polarized Hadronic Probes
Forschungszentrum Jülich
October 9, 2008 | Andro Kacharava (JCHP/IKP, FZ-Jülich)
Overview
COSY (Cooler Synchrotron) at Jülich (Germany)
• Introduction
• Polarized Hadrons
• COSY–Hardware
• COSY–Research
• Future Plans at COSY
• New Projects
• Hadronic probes: protons, deuterons
•
Polarization: beams & targets
• Summary
Hadron Physics: Understanding of all matter
comprised of quarks and gluons:
How does Nature make hadrons?
Evolution of our view of the nucleon
⇒ Experimental program with
polarized hadronic probes & strong theory support
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)
COSY Facility
Characteristics:
•
Energy range:
0.045 – 2.8 GeV (p)
0.023 – 2.3 GeV (d)
10 m
•
•
•
•
•
•
Max. momentum ~ 3.7 GeV/c
Energy variation (ramping mode)
Electron and Stochastic cooling
Internal and external beams
High polarization (p,d)
Spin manipulation
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)
COSY-Hardware (I): Polarized Internal Gas Target
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 ± 0.01
PZ = -0.96 ± 0.01
• Lamb-Shift Polarimeter (LSP)
• Storage Cell (SC) in target chamber
talk by R. Engels (session on Oct. 10)
COSY- Hardware (III): Detectors
ANKE
ANKE (double polarization):
- Magnetic spectrometer (3 dipoles)
- Internal beam
- (Un-), polarized target (PIT)
TOF
TOF (beam polarization):
- Non-magnetic (t-o-f) spectrometer
- Extracted beam
- Large acceptance
- Un- (polarized) cryo-targets
ANKE and TOF: no photon detection
COSY- Hardware (III): Detectors
WASA (beam polarization):
- Internal beam
- Electromagnetic calorimeter
- SC solenoid
- Inner and forward tracking
- Pellet target (unpolarized)
Charged particle and
WASA
photon detection
Relocation from CELSIUS to COSY in 2005
COSY- Hardware (III): Detectors
WASA (beam polarization):
- Internal beam
- Electromagnetic calorimeter
- SC solenoid
- Inner and forward tracking
- Pellet target (unpolarized)
Charged particle and
WASA-at-COSY
photon detection
Commissioning in 2006 – operational from 2007 on
COSY- Research (I): An Overview
Spectroscopy, Spin, Symmetry
Nuclear Forces
Hadronic Spectroscopy (N*´s, Exotics)
Strangeness
Role of s-Quark (OZI)
Symmetries
Symmetries and Symmetry Breaking
(ChS, P, C, IS)
In-medium
Modifications
Final State Interactions (Bound States)
…
isospin and polarization (beams, targets) as tools
(final state) photons as a probe (WASA)
COSY- Research (II): Selected Recent Results
Topics:
• NN-scattering
• Deuteron break-up
• Pion production
• η-3He interaction (FSI)
• Hyperon-Nucleon interaction
• Symmetry breaking
(1) NN – Interaction
NN – Interaction (I): The EDDA Legacy
• 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 (II): np System at ANKE
np system: different isospin channel
via Charge-Exchange duteron breakup:
→→
deuteron beam: dp→{pp}S (00)+n
→→
deuteron target: pd→{pp}S(1800)+n
• d beam: Tn up to 1.1 GeV for np
• d target: Tp up to 2.8 GeV for pn
n
→
d
D
→
↑n
p
↑p
↑ psp ↓ p
dp observables: dσ/dΩ, T20, T22, Cy,y,
quasi-free
np observables: Ay, Ayy, Dyy, Cxy,y,
Epp < 3 MeV
NN – Interaction (III): np Results at ANKE
→
dp→(pp)1S0 n
D.Chiladze et al. PLB 637, 170 (2006)
Axx (T22)
Transition from deuteron to (pp)1S0:
pn → np spin flip
Td = 1170 MeV
np spin-dependent amplitudes:
Ayy (T20)
dσ
2
2
2
2
, T20 , T22 ⇒ γ + β , δ , ε
dq
Results:
• Method works at Tn = 585 MeV
• Application to higher energies
• Td=2.23 GeV (in progress)
New !
Tn = 585 MeV
⇒ SAID np amplitudes
NN – Interaction (IV): np Results at ANKE
→
dp→(pp)1S0 n
D.Chiladze et al. PLB 637, 170 (2006)
Axx (T22)
Transition from deuteron to (pp)1S0:
pn → np spin flip
Td = 1170 MeV
np spin-dependent amplitudes:
Ayy (T20)
dσ
2
2
2
2
, T20 , T22 ⇒ γ + β , δ , ε
dq
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
→→
dp
Cy,y
Cx,x
COSY: from Pions to the Phi
(2) Meson Production
Meson production (II): Motivation
• Derive chiral three-body forces
from p-wave pion production
pd elastic
π
δ
RIKEN, KVI, ...
Ch. Hanhart et al., PRL 85, (2000)
• Very different kinematics, but
same δ : consistency check of
ChPT for NN → NNπ
p
π+
1S
δ
Experiment is scheduled for 2009
3S
1p
p
p
π-
p
(3S1 – 3D1) → 1S0p
(unknown)
δ
p
0→
IUCF
p
• Model-independent extraction
from
ANKE
data
→→
pd → pspppπ-
n
n
Role of 4Nπ contact term
Meson production (III): Diproton final state
Meson production:
pN→{pp}sX
X=π
X=(2π) (ABC effect), η
X=ω, φ (OZI)
Deuteron: bound (p+n) system, very well studied
• Diproton: free {pp}-pair in 1S0 state, E
< 3 MeV
pp
•
(ChPT)
By-product:
Inverse diproton photodisintegration
pp→{pp}sγ
▶ Same kinematics as np→
→dγ
γ
▶ M1 multipole is forbidden
New tool to study hadron interactions !
Next
Polarization observables (Ay, Ayy, Axx )
V.Komarov et al., PRL 101(2008)
PLB 661 (2008); PLB 635 (2006)
η- 3He Interaction (I): (Quasi-) bound state
d+p→3He+η: Total C.S.
T. Mersmann et al., PRL 98, 242301 (2007)
quasi- bound state vwithin
< 1MeV of threshold ?
• Precison data, “step function”: 0→ 400 nb w/i 0.5 MeV
• Implies large 3Heη scattering length (~ 10 fm)
η- 3He Interaction (II): (Quasi-) bound state
• d+p→ 3He+η:: Angular distr.
C. Wilkin et al., PLB 654, 92 (2007)
0.4
A big phase variation of the s-wave
0.3
→
d+p→ 3He+η: (analys. in progress)
dσ 1
2
2
= pp pη  A + 2 B 


dΩ 6
| A |2 =
pp
pη
(1− 2T20 )
dσ
dΩ
 B 2 − A2 
T20 = 2  2
2
 A + 2 B 
p
1
dσ
| B |2 = p (1+ T20 )
pη
dΩ
2
2
f s + pη2 C
2
0.2
0.1
-0
w/ phase variation
-0.1
-0.2
-0.3
→ →
d+p→ 3He+η: (next step)
Cy, y =
asymmetry factor α
indication for a quasi-bound state?
α = 2 pη
Re( f s*C )
2 Re(A * B)
2
A +2B
2
Phase determination
between A and B
0
20
40
60
80
η momentum pη [MeV/c]
100
η- 3He Interaction (III): η-Meson mass
PLB 619 (2005) 281
Precision data – but
inconsistency w/ new data !?
Further investigations at COSY:
→
d+p→3He+η ; ∆m~50 keV
(analysis in progress)
New technique !
Barrier bucket
RF solenoid
d
GEM:
pd → 3Heη
SATURNE:
pd → 3Heη
NA48:
π− p → η n
MAMI:
γp → ηp
KLOE:
φ→ηγ
CLEO:
Ψ(2s) → η J/ψ
RF-induced spin-resonance:
∆p/p ~ 3 · 10-5
γ=
f ·
1 §
⋅ ¨ 1 − res ¸
G ©
f0 ¹
EDDA
talk by M. Leonova (session on Oct. 10)
COSY-TOF: decay vertex (2 → 4)
Λ
(3) Strangeness DoF
Strangeness production (I): YN Interaction
p p K+ Y N (mostly COSY data)
PLB 649 , 252 (2007): PLB 652, 245 (2007)
▲●○
pp → pK+Λ
Importance of Final
State Interaction
Incoherent sum of
3S and 1S
1
0
FSI with unknown
relative strengths
Spin dependence of FSI
unknown
■□ pp → pK+Σ0
without FSI
with FSI
Strangeness production (II): YN Interaction
ΛN scattering length: singlet (as) and triplet (at) part separately
•
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
Spin/isospin dependence
• TOF: high-resolution single polarized
Method: dispersion relations
Theory precision is 0.3 fm
⇔
A. Gasparyan et al., PRC 69, 034006 (2004)
→
p+p→K+(Λp) at (θK,cm = 90°) ⇒ at
→→
ANKE: double polarized p+n→K+(Λn)
(1 – CNN)·σ at (θK,cm = 0°) ⇒
as
26
Future plans: Experiments with polarized probes
2005−2009
2010−2014
COSY proposal #152
ArXiv:nucl-ex/0511028
Future plans: Exploration WASA-at-COSY
Charge Symmetry Breaking
(subset of isospin symmetry)
E. Stephenson et al., PRL 91, 142302 (2003)
• Isospin violation in d+d→α+π0
d
0
+
d
→
α
0
→
0
+
π0
1
Goal: determination of p-wave contribution
at 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
Q ≈ 3.0 MeV
New projects: at COSY
• [email protected]: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
Existing Facility
HESR:
Hadron Physics
with Anti-Proton
Beams
New Part:
- Atomic Physics
- Nuclear Physics (RIB)
- Hadron Physics
- Nucleus Nucleus Coll.
-…
Floor Plan FAIR-Facility at GSI (Darmstadt), Germany
New projects: HESR upgrade (Polarized Antiprotons)
Method: Spin Filtering ⇒ proton polarization due to multi-pass
interaction with polarized targets (also works for antiprotons)
talk by E. Steffens (session on Oct. 8)
Physics: Transferse spin structure of the nucleon
talk by M. Anselmino (session on Oct. 7)
towards an asymmetric polarized antiproton-proton collider
• Depolarization of beams with
unpolarized targets (COSY)
• Polarization build-up (COSY)
• Antiprotons (AD at CERN)
talks: by F. Rathmann and
A. Nass (session on Oct. 7)
31
Summary
COSY - unique opportunities for hadron physics with
polarized 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)
The END
Thank you very much for your
- attention –
Many thanks to the conference
organizers !

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