The COSY Experiments ANKE, WASA, and TOF · The COSY Experiments ANKE, WASA, and TOF Dieter Grzonka...
Transcript of The COSY Experiments ANKE, WASA, and TOF · The COSY Experiments ANKE, WASA, and TOF Dieter Grzonka...
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The COSY Experiments
ANKE, WASA, and TOF
Dieter Grzonka , IKP-1
TOF
Cyclotron ANKE
WASA
10 m
ANKE, WASA, TOF
• Detector Setup
• Physics
• Examples
Summary and Outlook
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ANKE TOF
COSY: experimental installations for hadron physics
with well focussed physics program
internal
magnetic spectrometer
spin physics
internal
~ 4π detector
symmetries
external
geometry spectrometer
strangeness
WASA
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ANKE - Apparatus for Studies of Nucleon and Kaon Ejectiles
internal magnetic spectrometer,
C-type dipole, gap height 20 cm
tracking detectors: scintillators,
wire chambers,
Si-telescope close to target
clustertarget,
polarized atomic beam and storage cell
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ANKE Physics Program
measurements: meson production (π, η, η‘, ω, ϕ, K ) in pp, pd, dd reactions,
medium effects subthreshold K-prod., in medium ϕ width,
pA reactions, pn-system, d-breakup, n K+ Σ+, ...
example: η-mass determination
precise beam momentum determination
using spin resonance (Δp/p < 6 . 10-5 ) mη = 547.873 ± 0.005 ±0.027 MeV/c2
pd → 3He η
Phys.Rev.D85 (2012) 112011
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ANKE Physics Program
focus: spin dependence of NN interaction and pion production
→ detailed understanding of nuclear forces and reactions
at intermediate energies
d p → {pp}s n : sensitive to spin-spin term in np → pn amplitude
d p → {pp}s n →
→
impulse
approximation
with SAID
amplitudes
d p → {pp}s n
d p → {pp}s n → →
→ polarization data
needed
[A. Kacharava, C. Wilkin, arXiv:1212.2771]
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ANKE Physics Program
accepted and proposed experiments
p d → p d η (→ dη scattering length, η-A bound states )
continuation of the spin program
double polarization, spin correlations
measurements with logitudinal spin
→ Sibirian snake
p p → pp / →
p d → p d →
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WASA - Wide Angle Shower Apparatus
tracking detectors: scintillators, wire chambers,
EM calorimeter (CsI),
Pellet target, thin wall SC magnet (1T)
close to 4π detection system for
charged particles and photons
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WASA Physics Program
tests of fundamental symmetries
isospin symmetry
C, CP, CPT symmetry
transition form factors
meson production dynamics
exotic states
main area: meson decay studies (π0, η, ω)
via : pp→pp M and pd→3He M
experimental aspects:
pp : high production rate
high background
pd: low background
low production rate
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WASA Physics Program
tests of fundamental symmetries
isospin symmetry
C, CP, CPT symmetry
transition form factors
meson production dynamics
exotic states
main area: meson decay studies (π0, η, ω)
via : pp→pp M and pd→3He M
experimental aspects:
pp : high production rate
high background
pd: low background
low production rate
e.g. η production
inclusive
pd → 3He X „inclusive“
pp → pp X
η identification: missing mass=√(Ein−Eout )2−(Pin−Pout )
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WASA Physics Program
tests of fundamental symmetries
isospin symmetry
C, CP, CPT symmetry
transition form factors
meson production dynamics
exotic states
main area: meson decay studies (π0, η, ω)
via : pp→pp M and pd→3He M
experimental aspects:
pp : high production rate
high background
pd: low background
low production rate
e.g. η production
inclusive
pd → 3He X „inclusive“
pp → pp X
pp → pp X
X → π+π-π0 channel selection
η identification: missing mass=√(Ein−Eout )2−(Pin−Pout )
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WASA Physics Program
tests of fundamental symmetries
isospin symmetry
C, CP, CPT symmetry
transition form factors
meson production dynamics
exotic states
main area: meson decay studies (π0, η, ω)
via : pp→pp M and pd→3He M
experimental aspects:
pp : high production rate
high background
pd: low background
low production rate
e.g. η production
available data:
pd → 3He η 3 . 106 η (reconstructed)
pp → pp η 5 . 108 η (produced)
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meson decay studies at WASA
η → π0 π0 π0
/ π+ π- π0
→ π+ π- γ
→ π+ π- e+e-
→ e+ e- e+ e- / γ e+ e-
→ e+ e-
→ e+ e-
→ π0 e+ e-
→ π+ π- π0
→ π+ π-
isopspin breaking decay, sensitive to mu-md
Dalitz plot parameters, ππ scattering parameter
box anomaly π+
γ
π-
η
CP violation (virtual photon asymmetry)
transition form factor
physics beyond SM (BR ~ 10-9 )
physics beyond SM , discrepancy between KTEV data and theory
transition form factor, deviation from VMD prediction
π0
ω
triangle / box anomaly, fsi
ρ-ω interference
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Experiments at WASA
analysis of pp data:
increased statistics by an order of magnitude
η → π+ π- e+ e- (PDG:
br = 2.68 ±0.11 . 10-4 )
WASA preliminary (±0.27stat±0.22sys
. 10-4 )
Theory
br = 3.1 . 10-4
KLOE : Aϕ = -0.6 (±3.1) % theory : Aϕ < 1 %
WASA preliminary: Aϕ = 0.4 (±9±3) %
(D. Coderre)
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Experiments at WASA
analysis of pp data:
increased statistics by an order of magnitude
η → π+ π- e+ e- (PDG:
br = 2.68 ±0.11 . 10-4 )
WASA preliminary (±0.27stat±0.22sys
. 10-4 )
Theory
br = 3.1 . 10-4
KLOE : Aϕ = -0.6 (±3.1) % theory : Aϕ < 1 %
WASA preliminary: Aϕ = 0.4 (±9±3) %
(D. Coderre)
ABC effect
enhancement at low mass region of Mππ
observed in: pn → dπ0π0 / dπ+π-
pd → 3He π0π0 / 3He π+π-
dd → 4He π0π0 / 4He π+π-
pn → R → ΔΔ → d π0π0
I(JP) = 0 (3+), m = 2.38 GeV , Γ = 70 MeV
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TOF – Time Of Flight Spectrometer
lH2 target
Ø 6 mm
up to 9 m with
additional moduls
tracking of charged particles
vertex reconstruction, delayed decays
→ event reconstruction from geometry / tof
neutral particle detection → missing mass,
neutron detector in forward direction
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TOF – Time Of Flight Spectrometer
Reaction channels studied at TOF
pp → pp γ
π0
π+π-
η
ω
pp → pp π+π-
ω
dp → pp pπ-
pp → p K+ Λ
p K+ Σ0
p K0 Σ+
n K+ Σ+
pd → p p K0 Λ
pp → p K+ Λ
pd → p p K0 Λ
present studies:
hyperon production
•high statistics
(Dalitz plot analysis)
p K+ Λ events:
150k at 2.7 GeV/c
120k at 2.95 GeV/c
•polarization observables
polarized beam
(≤70% polarization)
self-analyzing weak decay
Λ→ p π-
→ PN, AN , DNN
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The pKΛ – Dalitz plot
N*(1650)
N*(1720)
FSI
P(p-Λ) low
cusp
mpΛ at NΣ threshold
Data 2010 (2.95 GeV/c)
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The pKΛ – Dalitz plot
N*(1650)
N*(1720)
P(p-Λ) low
mpΛ at NΣ threshold
Data 2010 (2.95 GeV/c)
2.7 GeV/c
2.9 GeV/c
3.1 GeV/c
3.3 GeV/c
N*(1650)
N*(1720)
mΛp2 / GeV2/c2
mΛ
K2 /
GeV
2/c
2
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Comparison of 2.7 GeV/c and 2.95 GeV/c Data
strong FSI (→ extraction of scattering length
a= -1.28 ±0.11±0.3 )
N* strong at 2.95 GeV/c, weak at 2.7 GeV/c pΣ cusp effect not visible at 2.7 GeV/c
2.95 GeV/c data: M. Röder,
2.7 GeV/c data : F. Hauenstein
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Comparison of 2.7 GeV/c and 2.95 GeV/c Data
strong FSI (→ extraction of scattering length
a= -1.28 ±0.11±0.3 )
N* strong at 2.95 GeV/c, weak at 2.7 GeV/c pΣ cusp effect not visible at 2.7 GeV/c
2.95 GeV/c data: M. Röder,
2.7 GeV/c data : F. Hauenstein
Λ polarization
2.95 GeV/c
2.7 GeV/c
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ANKE TOF WASA
Summary
magnetic spectrometer
large acceptance
in forward direction
precise momentum reconstruction
polarized targets
spin physics
~ 4π detector for charged particles
and photons
pellet target → high luminosities
rare decay studies
symmetries
geometry spectrometer
precise tracking
reconstruction of delayed decays
hyperon production
strangeness
precise COSY beam combined with optimized detector installations
→ improved understanding of hadron physics
double polarization studies,
including logitudinal spin
( Sibirian snake )
π0 → e+ e- (physics beyond SM),
d d → α π0 (isospin violation)
data analysis
Outlook data analysis
pp → p K+ Λ
(→ at )
pd → p p K0 Λ
→
→