with polarized hadronic probesphysics program at cosy-jülich · 2008. 10. 3. · october 9, 2008 |...
TRANSCRIPT
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 !