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Measurement of the double polarization observables G in pionphotoproduction off the proton
Karsten Spieker
Helmholtz-Institut für Strahlen- und KernphysikUniversity of Bonn, Germany
September 21th, 2015
Content Helmholtz-Institut für Strahlen- und Kernphysik
1 Motivation
2 Experimental setup
3 Selection of Events
4 Extraction of the polarization observables
5 Results of the polarization observables
6 Summary and outlook
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 2
Motivation Helmholtz-Institut für Strahlen- und Kernphysik
Excitation spectrum of the nucleons
What is matter made of?
molecules atom nucleus nucleon quark
Motivation: Analogy to atomic spectroscopy
Neon emission spectrum
→ Direct information on the dynamics of the atom, i.e. fine structure!
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 3
Motivation Helmholtz-Institut für Strahlen- und Kernphysik
Excitation spectrum of the nucleons
What is matter made of?
molecules atom nucleus nucleon quark
Nucleon spectroscopy (open questions)
• Excitation spectrum of the nucleon provides information about interaction/dynamics ofconstituents
• How many degrees of freedom:
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 3
Motivation Helmholtz-Institut für Strahlen- und Kernphysik
Excitation spectrum of the nucleons
What is matter made of?
molecules atom nucleus nucleon quark
Nucleon spectroscopy (photoproduction)total photoabsorption cross section on the proton
0 500 1000 1500 2000 2500 3000Eγ [MeV]
100200300400500600700
σ[µ
b]
→ Due to short life time, broad and overlapping resonances!→ NO direct information on the dynamics of the constituents!
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 3
Motivation Helmholtz-Institut für Strahlen- und Kernphysik
Excitation spectrum of the nucleons
How to analyze the excitation spectrum?
• Study γN → N∗/∆∗ → N π0,N η,N η′, ,N π0π0,N π+π− · · ·• Experiments, e.g., Crystal Ball@MAMI, Crystal Barrel@ELSA, CLAS@Jefferson Lab
• Theory vs Experiment: most resonances found via πN → N∗/∆∗ → X
[E.D. Bloom et. al., SLAC-PUB-653 (1969)]
[CB-ELSA]
[SAPHIR-ELSA]
[A2-MAMI]
[U. Loering et al., Eur.Phys.J. A, 10:395-446, 2001]
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 4
Motivation Helmholtz-Institut für Strahlen- und Kernphysik
Polarization observables
• Scattering amplitude can be described by 4 complex amplitudes (CGLN-amplitudes)• These CGLN-amplitudes can be described by multipoles• These multipoles are directly related to polarization observables
Overview of the polarization observables in the 2-body kinematic system for thephotoproduction of a pseudoscalar meson
Photonpolarization
Targetpolarization
Recoil nucleonpolarization
Target and recoilpolarizations
X Y Z(beam) X’ Y’ Z’ X’ X’ Z’ Z’X Z X Z
unpolarizedlinearcircular
σσσσΣΣΣΣ-
- T -H (-P) GF - E
- P -
Ox' (-T) Oz'Cx' - Cz'
Tx' Lx' Tz' Lz'(-Lz') (Tz') (Lx') (-Tx')- - - -
---
• Note: σ, Σ,T, P + 4 double polarization observables are needed for model independentsolution
[W. Chiang and F. Tabakin, Phys. Rev., C55 (1997) 2054-2066]
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 5
Motivation Helmholtz-Institut für Strahlen- und Kernphysik
Multipole expression of G for l ≤ 1 in single pion photoproduction off the proton
dσdΩ· G(cos θ) = ImM∗1−(E1+ −M1+)− 2E∗1+M1+ · 3 sin2 θ
≈ ImM1−ReM1+ · 3 sin2 θ
solid line: real part, dotted lines: imaginary part
→ sensitive to the M1− partial wave→ sensitive to Roper Resonance
P11(1440)!
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 6
Motivation Helmholtz-Institut für Strahlen- und Kernphysik
Comparison of dominant multipole contributions from the different PWA
[10−
18m
]
— BG2011-02 — BG2014-02 — MAID-07 - - - SAID-SN11 — SAID-CM12 — JüBn-2014
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 7
Motivation Helmholtz-Institut für Strahlen- und Kernphysik
Sensitivity studies of the BnGa PWA for the 2π0 channel off the proton
)π2θcos(-1 -0.5 0 0.5 1
G
-0.4
-0.3
-0.2
-0.1
0
0.1 = (430-490) MeVγE
)π2θcos(-1 -0.5 0 0.5 1
G
-0.4
-0.3
-0.2
-0.1
0
0.1 = (610-670) MeVγE )π2θcos(-1 -0.5 0 0.5 1
G
-0.4
-0.3
-0.2
-0.1
0
0.1 = (490-550) MeVγE
)π2θcos(-1 -0.5 0 0.5 1
G
-0.4
-0.3
-0.2
-0.1
0
0.1 = (670-730) MeVγE )π2θcos(-1 -0.5 0 0.5 1
G
-0.4
-0.3
-0.2
-0.1
0
0.1 = (550-610) MeVγE
)π2θcos(-1 -0.5 0 0.5 1
G
-0.4
-0.3
-0.2
-0.1
0
0.1 = (730-790) MeVγE
-1 -0.5 0 0.5 1-1 -0.5 0 0.5 1
π2θcos -1 -0.5 0 0.5 1
-0.4
-0.3
-0.2
-0.1
0
0.1
G
-0.4
-0.3
-0.2
-0.1
0
0.1
BG2014-01 [1]BG2014-02 [1]
S/D-wave ratio decay of D13(1520)→ ∆πBG2014-01: S/D=3BG2014-02: S/D=1.5 [1] E. Gutz et al, Eur. Phys. J. A50 (2014) 74
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 8
Experimental setup Helmholtz-Institut für Strahlen- und Kernphysik
A2@MAMI
long. polarized electrons incident on diamond crystal in combination with long. polarizedbutanol target
→ Measurement of G & E at the same time!→ Perfectly suited to identify charged and neutral final states!
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 9
Experimental setup Helmholtz-Institut für Strahlen- und Kernphysik
A2@MAMI
long. polarized electrons incident on diamond crystal in combination with long. polarizedbutanol target
linearly polarized photons
(MeV)γE200 400 600 800 1000 1200 1400
lδ
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
for different coherent edges
→ Measurement of G & E at the same time!→ Perfectly suited to identify charged and neutral final states!
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 9
Experimental setup Helmholtz-Institut für Strahlen- und Kernphysik
A2@MAMI
long. polarized electrons incident on diamond crystal in combination with long. polarizedbutanol target
circularly polarized photons
[MeV]γE400 600 800 1000 1200 1400
γp
0.2
0.3
0.4
0.5
0.6
0.7
0.8
pγ =4EγE0−E2
γ
4E20−4EγE0+3E2
γ· pe
with pe ≈ 77% (Mott-polarimeter)
→ Measurement of G & E at the same time!→ Perfectly suited to identify charged and neutral final states!
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 9
Experimental setup Helmholtz-Institut für Strahlen- und Kernphysik
A2@MAMI
long. polarized electrons incident on diamond crystal in combination with long. polarizedbutanol target
longitudinally polarized target
→ Measurement of G & E at the same time!→ Perfectly suited to identify charged and neutral final states!
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 9
Experimental setup Helmholtz-Institut für Strahlen- und Kernphysik
A2@MAMI
long. polarized electrons incident on diamond crystal in combination with long. polarizedbutanol target
carbon target for background studies
→ Measurement of G & E at the same time!→ Perfectly suited to identify charged and neutral final states!
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 9
Selection of Events Helmholtz-Institut für Strahlen- und Kernphysik
Kinematic Cuts
γ p → p π0 → p 2γ
→ 2 neutral particles + 1 charged particle in the final state!
Mass Cuts
• Cut on the proton mass: mmm = (938± 3σ(Eγ)) MeV• Cut on the meson mass: mγγ = (135± 3σ(Eγ)) MeV
Sun Sep 20 10:27:12 2015 [MeV]mmm
400 600 800 1000 1200 1400 1600
#
0
2000
4000
6000
8000 : 20.39σ: 932.77, µ < -0.11θ -0.22 < cos Eγ = 464 − 497 MeV
P R E L I M I N A R Y
Sun Sep 20 16:19:47 2015 [MeV]γ γm
0 50 100 150 200 250
#
0
1000
2000
3000 < -0.11θ -0.22 < cos
Eγ = 464 − 497 MeV
P R E L I M I N A R Y
— butanol — scaled carbon — reconstructed hydrogen — fit function
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 10
Selection of Events Helmholtz-Institut für Strahlen- und Kernphysik
Kinematic Cuts
Angular Cuts
π0
pϕπ
θπ
• Reaction products decay in one plane:φdiff = |φπ − φp| = (180± 3σ)
• Comparison of the calculated &reconstructed proton polar angle:θdiff = |θcal − θrec | = (0± 3σ)
Sun Sep 20 10:48:32 2015
[deg]p
φ-πφ100 120 140 160 180 200 220 240 260
#
0
1000
2000
3000: 6.10σ: 179.04, µ < -0.11θ -0.22 < cos
Eγ = 464 − 497 MeV
P R E L I M I N A R Y
Sun Sep 20 10:54:12 2015
[deg]p,recθ-p,calcθ-40 -30 -20 -10 0 10 20 30 40
#
0
2000
4000
6000 : 3.36σ: 0.27, µ < -0.11θ -0.22 < cos Eγ = 464 − 497 MeV
P R E L I M I N A R Y
— butanol — scaled carbon — reconstructed hydrogen — fit function
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 11
Extraction of the polarization observables Helmholtz-Institut für Strahlen- und Kernphysik
Angular distribution NB(θ, φ)
• Butanol (C4H9OH) has unpolarized protons in carbon and oxygen
NB
∣∣∣∣±Λz
±α
(θ, φ) = (
NB︷ ︸︸ ︷NH + NC )(θ)·
((1−
ΣB︷ ︸︸ ︷(NH ΣH + NC ΣC
NH + NC
)δl cos 2(φ−α)+
dilution factor D︷ ︸︸ ︷(NH
NH + NC
)δl Λz GH sin 2(φ−α)
)
→ ΣB contains distribution from bound protons
→ Double polarization observable G requires longitudinally polarized target→ Find thefraction of reaction on polarized protons→ Dilution factor
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 12
Extraction of the polarization observables Helmholtz-Institut für Strahlen- und Kernphysik
Angular distribution NB(θ, φ)
NB
∣∣∣∣±Λz
±α
(θ, φ) = (
NB︷ ︸︸ ︷NH + NC )(θ)·
((1−
ΣB︷ ︸︸ ︷(NH ΣH + NC ΣC
NH + NC
)δl cos 2(φ−α)+
dilution factor D︷ ︸︸ ︷(NH
NH + NC
)δl Λz GH sin 2(φ−α)
)
Dilution FactorEγ = (464-497) MeV
D =NH
NH + NC=
NH
NB=
NB − s(Eγ)NC
NB= 1− s(Eγ)
NC
NBwith NB ≈ NH + NC
[deg]p
φ-πφ100 120 140 160 180 200 220 240 260
#
0
1000
2000
3000
P R E L I M I N A R Y
)πθcos(-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1
dilu
tio
n f
acto
r D
00.10.20.30.40.50.60.70.80.9
1
P R E L I M I N A R Y
— butanol — scaled carbonKarsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 13
Extraction of the polarization observables Helmholtz-Institut für Strahlen- und Kernphysik
Angular distribution NB(θ, φ)
NB
∣∣∣∣±Λz
±α
(θ, φ) = (
NB︷ ︸︸ ︷NH + NC )(θ)·
((1−
ΣB︷ ︸︸ ︷(NH ΣH + NC ΣC
NH + NC
)δl cos 2(φ−α)+
dilution factor D︷ ︸︸ ︷(NH
NH + NC
)δl Λz GH sin 2(φ−α)
)
φ-asymmetries for different settingsEγ = (464-497) MeV and−0.22 < cos θπ ≤ −0.11
[deg]πφ -150 -100 -50 0 50 100 150
6080
100120140160180200220240
[deg]πφ -150 -100 -50 0 50 100 150
80100120140160180200220240260
[deg]πφ -150 -100 -50 0 50 100 150
60
80
100
120
140
160
180
200
[deg]πφ -150 -100 -50 0 50 100 150
406080
100120140160180200
α = −45 and Λz ↑ α = −45 and Λz ↓
α = +45 and Λz ↑ α = +45 and Λz ↓
P R E L I M I N A R Y
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 14
Extraction of the polarization observables Helmholtz-Institut für Strahlen- und Kernphysik
Absolute normalized determination
• Sum of different φ-asymmetries results in unpolarized cross section→ Normalize the different settings before they are shifted!
NB(θ, φ)′ = 1− ΣBδl cos 2φ+ Dδl ΛzGH sin 2φ
f (θ, φ) = 1 + B cos 2φ+ C sin 2φ
Shifted and normalized φ-asymmetries and their sumEγ = (464-497) MeV and−0.22 < cos θπ ≤ −0.11
[deg]πφ -150 -100 -50 0 50 100 1500
0.1
0.2
0.3
0.4
0.5
[deg]πφ -150 -100 -50 0 50 100 1500
0.1
0.2
0.3
0.4
0.5
[deg]πφ -150 -100 -50 0 50 100 1500
0.1
0.2
0.3
0.4
0.5
[deg]πφ -150 -100 -50 0 50 100 1500
0.1
0.2
0.3
0.4
0.5
α = −45 and Λz ↑ α = −45 and Λz ↓
α = +45 and Λz ↑ α = +45 and Λz ↓
P R E L I M I N A R Y
[deg]πφ -150 -100 -50 0 50 100 150
0.6
0.8
1
1.2
1.4
P R E L I M I N A R Y
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 15
Results of the polarization observables Helmholtz-Institut für Strahlen- und Kernphysik
Beam asymmetry ΣB - Comparison with recent results
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (266-299) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (365-398) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (464-497) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (563-596) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (662-695) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (761-794) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (299-332) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (398-431) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (497-530) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (596-629) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (695-728) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (794-827) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (332-365) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (431-464) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (530-563) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (629-662) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (728-761) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (827-860) MeVγE
-1 -0.5 0 0.5 1-1 -0.5 0 0.5 1
πθcos -1 -0.5 0 0.5 1
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1
Σ
-1-0.5
00.5
1
P R E L I M I N A R Y
MAMI [1] GRAAL [2] • this work
[1] R. Beck et al, Eur. Phys. J. A28 (2006) 173-183 [2] O.Bartalini et al., Eur. Phys.J. A26 (2005) 399
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 16
Results of the polarization observables Helmholtz-Institut für Strahlen- und Kernphysik
Beam asymmetry ΣB - Comparison with PWA solutions
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (266-299) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (365-398) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (464-497) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (563-596) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (662-695) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (761-794) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (299-332) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (398-431) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (497-530) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (596-629) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (695-728) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (794-827) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (332-365) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (431-464) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (530-563) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (629-662) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (728-761) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1
= (827-860) MeVγE
-1 -0.5 0 0.5 1-1 -0.5 0 0.5 1
πθcos -1 -0.5 0 0.5 1
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1
Σ
-1-0.5
00.5
1
P R E L I M I N A R Y
— BG2014-01 [1] — BG2014-02 [1] — MAID-07 [2] — SAID-CM12 [3] • this work
[1] E. Gutz et al, Eur. Phys. J. A50 (2014) 74 [2] D. Drechsel, S. S. Kamalov, and L. Tiator, Eur. Phys. J. A34, (2007) 69-97[3] R. Workman et al, Phys. Rev. C86, (2012) 015202
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 17
Results of the polarization observables Helmholtz-Institut für Strahlen- und Kernphysik
Double polarization observable G - Comparison with recent results
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (266-299) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (365-398) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (464-497) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (563-596) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (662-695) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (761-794) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (299-332) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (398-431) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (497-530) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (596-629) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (695-728) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (794-827) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (332-365) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (431-464) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (530-563) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (629-662) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (728-761) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (827-860) MeVγE
-1 -0.5 0 0.5 1-1 -0.5 0 0.5 1
πθcos -1 -0.5 0 0.5 1
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1
G
-1-0.5
00.5
1
P R E L I M I N A R Y
CBELSA/TAPS [1] • this work
[1] A. Thiel et al., Phys. Rev. Lett. 109 (2012) 102001
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 18
Results of the polarization observables Helmholtz-Institut für Strahlen- und Kernphysik
Double polarization observable G - Comparison with PWA solutions
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (266-299) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (365-398) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (464-497) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (563-596) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (662-695) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (761-794) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (299-332) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (398-431) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (497-530) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (596-629) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (695-728) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (794-827) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (332-365) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (431-464) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (530-563) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (629-662) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (728-761) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (827-860) MeVγE
-1 -0.5 0 0.5 1-1 -0.5 0 0.5 1
πθcos -1 -0.5 0 0.5 1
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1
G
-1-0.5
00.5
1
P R E L I M I N A R Y
— BG2014-01 [1] — BG2014-02 [1] — MAID-07 [2] — SAID-CM12 [3] • this work
[1] E. Gutz et al, Eur. Phys. J. A50 (2014) 74 [2] D. Drechsel, S. S. Kamalov, and L. Tiator, Eur. Phys. J. A34, (2007) 69-97[3] R. Workman et al, Phys. Rev. C86, (2012) 015202
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 19
Summary and outlook Helmholtz-Institut für Strahlen- und Kernphysik
Summary:
• Selection of the reaction ~γ~p → p π0
• Measurement of the beam asymmetry ΣB and double polarization observable G in thesingle π0 channel
• Good agreement with recent results for the beam asymmetry ΣB and doublepolarization observable G
Outlook:
• Extracted the polarization observable E
• Analysis of nπ+ channel (Isospin seperation of M1− partial wave)
• Analysis of 2π0 channel (G & E is very sensitive on D13(1520) resonance)
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 20
Outlook Helmholtz-Institut für Strahlen- und Kernphysik
2π0 selection - Some first results
2-dimensional invariant mass distribution of the photon pairs
without any cuts
[MeV] 2γ 1 γ m0 50 100 150 200 250 300 350
[M
eV]
4
γ 3
γ
m
0
50
100
150
200
250
300
350
1
10
210
310
410
(#events ≈ 750.000)
PRELIMINARY
with all introduced cuts
[MeV] 2γ 1 γ m0 50 100 150 200 250 300 350
[M
eV]
4
γ 3
γ
m
0
50
100
150
200
250
300
350
1
10
210
310
invariante Massen gegeneinander(Cut: All(Signal)(#events ≈ 116.000)
PRELIMINARY
However: Still huge combinatorial background.→ Use APLCON[1] fitter for solving this problem.[1] http://www.desy.de/ blobel/wwwcondl.html
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 21
Outlook Helmholtz-Institut für Strahlen- und Kernphysik
2π0 selection - CL and result
Convidence Level (CL) and 2-dimensional invariant mass distribution of the photonpairs
CL 0 0.2 0.4 0.6 0.8 1
#
0
5
10
15310× p0 7.5± 597.4
p1 11.8652± 0.5802
PRELIMINARY
with all cuts + CL>0.01
[MeV] 2γ 1 γ m0 50 100 150 200 250 300 350
[M
eV]
4
γ 3
γ
m0
50
100
150
200
250
300
350
1
10
210
PRELIMINARY
(#events ≈ 67.000)
"The important thing is not to stop questioning.Curiosity has its own reason for existing."
(Albert Einstein, 1879-1955)
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 22
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Double polarization observable E
Helicity dependent cross section
N∣∣∣∣1/2
3/2
(θ) = N0 · (1± DδcΛzE)
→ E =1D
1δc
1Λz
N1/2 − N3/2
N1/2 + N3/2
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 23
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Double polarization observable E - Comparison with PWA solutions
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (220-260) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (340-380) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (460-500) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (580-620) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (700-740) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (260-300) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (380-420) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (500-540) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (620-660) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (740-780) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (300-340) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (420-460) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (540-580) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (660-700) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (780-820) MeVγE
-1 -0.5 0 0.5 1-1 -0.5 0 0.5 1
πθcos -1 -0.5 0 0.5 1
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1-1
-0.50
0.51
E
-1-0.5
00.5
1
P R E L I M I N A R Y
— BG2014-01 [1] — BG2014-02 [1] — MAID-07 [2] — SAID-CM12 [3] • this work CBELSA/TAPS [4]
[1] E. Gutz et al, Eur. Phys. J. A50 (2014) 74 [2] D. Drechsel, S. S. Kamalov, and L. Tiator, Eur. Phys. J. A34, (2007) 69-97[3] R. Workman et al, Phys. Rev. C86, (2012) 015202 [4] M. Gottschall et al., Phys. Rev. Lett. 112 (2014) 012003
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 24
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Double polarization observable E - Comparison with PWA solutions
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (820-860) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (940-980) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1060-1100) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1180-1220) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1300-1340) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (860-900) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (980-1020) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1100-1140) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1220-1260) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1340-1380) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (900-940) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1020-1060) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1140-1180) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1260-1300) MeVγE
πθcos -1 -0.5 0 0.5 1
E
-1
-0.5
0
0.5
1 = (1380-1420) MeVγE
-1 -0.5 0 0.5 1-1 -0.5 0 0.5 1
πθcos -1 -0.5 0 0.5 1
-1-0.5
00.5
1-1
-0.50
0.51
-1-0.5
00.5
1-1
-0.50
0.51
E
-1-0.5
00.5
1
P R E L I M I N A R Y
— BG2014-01 [1] — BG2014-02 [1] — MAID-07 [2] — SAID-CM12 [3] • this work CBELSA/TAPS [4]
[1] E. Gutz et al, Eur. Phys. J. A50 (2014) 74 [2] D. Drechsel, S. S. Kamalov, and L. Tiator, Eur. Phys. J. A34, (2007) 69-97[3] R. Workman et al, Phys. Rev. C86, (2012) 015202 [4] M. Gottschall et al., Phys. Rev. Lett. 112 (2014) 012003
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 25
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Double polarization observable E in η-photoproduction
θcos-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
1.5
=750 MeVγE
θcos-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
1.5
=1050 MeVγE
θcos-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
1.5
=1350 MeVγE
θcos-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
1.5
=850 MeVγE
θcos-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
1.5
=1150 MeVγE
θcos-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
1.5
=950 MeVγE
θcos-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
1.5
=1250 MeVγE
-1 -0.5 0 0.5 1
-1 -0.5 0 0.5 1
CMSθcos -1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
1.5-1
-0.5
0
0.5
1
1.5-1
-0.5
0
0.5
1
1.5
CMSθcos
P R E L I M I N A R Y
— BG2014-01 [1] — BG2014-02 [1] — η MAID — SAID-GE09 • A2 [2] • CBELSA/TAPS [3]
[1] E. Gutz et al, Eur. Phys. J. A50 (2014) 74 [2] F. Afzal [3] J.Müller et al., to be published soon)
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 26
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Sensitivity studies - BnGa
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (430-490) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (610-670) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (790-850) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (970-1030) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (1150-1210) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (1330-1390) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (490-550) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (670-730) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (850-910) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (1030-1090) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (1210-1270) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (1390-1450) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (550-610) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (730-790) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (910-970) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (1090-1150) MeVγE
-1 -0.5 0 0.5 1
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
= (1270-1330) MeVγE
-1 -0.5 0 0.5 1-1 -0.5 0 0.5 1
π2θcos -1 -0.5 0 0.5 1
-0.50
0.51-0.50
0.51-0.50
0.51-0.50
0.51
-0.50
0.51
E
-0.50
0.51
BG2014-01BG2014-02
S/D-wave ratio decay of D13(1520)→ ∆πBG2014-01: S/D=3BG2014-02: S/D=1.5
S/D-wave ratio decay of D33(1940)→ ∆πBG2014-01: S/D=1/5BG2014-02: S mostly
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 27
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Pull-distributionsConstant 12.3± 2297 Mean 0.005± 0.194 Sigma 0.005± 1.117
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
500
1000
1500
2000
2500Constant 12.3± 2297 Mean 0.005± 0.194 Sigma 0.005± 1.117
pullbeam_E
Constant 25.4± 9225
Mean 0.00255± -0.03041 Sigma 0.002± 1.031
-10 -8 -6 -4 -2 0 2 4 6 8 100
2000
4000
6000
8000
10000Constant 25.4± 9225
Mean 0.00255± -0.03041 Sigma 0.002± 1.031
pullgamma_Ecb Constant 26.2± 9537
Mean 0.00226± -0.05156 Sigma 0.002± 1.019
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
2000
4000
6000
8000
10000
Constant 26.2± 9537
Mean 0.00226± -0.05156 Sigma 0.002± 1.019
pullgamma_thetacb Constant 25.0± 9298
Mean 0.00230± 0.02536 Sigma 0.002± 1.053
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
2000
4000
6000
8000
10000Constant 25.0± 9298
Mean 0.00230± 0.02536 Sigma 0.002± 1.053
pullgamma_phicb
Constant 6.6± 651.8 Mean 0.00972± -0.07162 Sigma 0.01± 1.07
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
100
200
300
400
500
600
700
800
Constant 6.6± 651.8 Mean 0.00972± -0.07162 Sigma 0.01± 1.07
pullgamma_Etaps Constant 7.4± 716 Mean 0.0082± -0.1816 Sigma 0.0072± 0.9947
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
100
200
300
400
500
600
700
800
Constant 7.4± 716 Mean 0.0082± -0.1816 Sigma 0.0072± 0.9947
pulls_4g_TAPS Constant 6.6± 665.5 Mean 0.00873± 0.02606 Sigma 0.007± 1.086
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
100
200
300
400
500
600
700
Constant 6.6± 665.5 Mean 0.00873± 0.02606 Sigma 0.007± 1.086
pullgamma_phitaps
Constant 11.6± 2010 Mean 0.00494± -0.09238 Sigma 0.004± 1.011
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
500
1000
1500
2000
Constant 11.6± 2010 Mean 0.00494± -0.09238 Sigma 0.004± 1.011
pullproton_thetacb Constant 10.6± 1878 Mean 0.00519± -0.08089 Sigma 0.004± 1.095
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
500
1000
1500
2000Constant 10.6± 1878 Mean 0.00519± -0.08089 Sigma 0.004± 1.095
pullproton_phicb
Constant 6.2± 548.2 Mean 0.0094± -0.2653 Sigma 0.008± 1.041
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
100
200
300
400
500
600
Constant 6.2± 548.2 Mean 0.0094± -0.2653 Sigma 0.008± 1.041
pullproton_thetataps Constant 6.1± 560.6 Mean 0.00910± -0.07881 Sigma 0.007± 1.022
-10 -8 -6 -4 -2 0 2 4 6 8 10
0
100
200
300
400
500
600
Constant 6.1± 560.6 Mean 0.00910± -0.07881 Sigma 0.007± 1.022
pullproton_phitaps
P R E L I M I N A R Y
not fitted
not fitted
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 28
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Energy dependent selection - Theta
-40 -30 -20 -10 0 10 20 30 400
200400600800
1000120014001600
: 1.69σ: -1.62, µ 233-266 MeVγE
-40 -30 -20 -10 0 10 20 30 400
50010001500200025003000350040004500
: 1.60σ: -1.82, µ 266-299 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
10000 : 2.24σ: -1.66, µ 299-332 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
100001200014000 : 3.85σ: -0.78, µ 332-365 MeVγE
-40 -30 -20 -10 0 10 20 30 400
50001000015000200002500030000
: 3.98σ: -0.09, µ 365-398 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
100001200014000160001800020000
: 3.89σ: 0.15, µ 398-431 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
100001200014000160001800020000 : 3.81σ: 0.32, µ 431-464 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
1000012000 : 3.69σ: 0.66, µ 464-497 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
10000 : 3.64σ: 0.73, µ 497-530 MeVγE
-40 -30 -20 -10 0 10 20 30 400
100020003000400050006000700080009000 : 3.53σ: 0.85, µ 530-563 MeVγE
-40 -30 -20 -10 0 10 20 30 400
1000200030004000500060007000
: 3.48σ: 0.82, µ 563-596 MeVγE
-40 -30 -20 -10 0 10 20 30 400
50010001500200025003000350040004500 : 3.75σ: 0.99, µ 596-629 MeVγE
-40 -30 -20 -10 0 10 20 30 400
50010001500200025003000 : 3.88σ: 0.96, µ 629-662 MeVγE
-40 -30 -20 -10 0 10 20 30 400
5001000150020002500300035004000 : 3.70σ: 0.80, µ 662-695 MeVγE
-40 -30 -20 -10 0 10 20 30 400
500100015002000250030003500 : 3.96σ: 0.90, µ 695-728 MeVγE
[MeV]γE300 400 500 600 700
[d
eg]
θ ∆
-20-15-10-505
101520
energy dependent cut rangesenergy dependent cut ranges
— butanol — scaled carbon — reconstructed hydrogen — fit function
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 29
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Energy dependent selection - Theta
-40 -30 -20 -10 0 10 20 30 400
200400600800
1000120014001600
: 1.69σ: -1.62, µ 233-266 MeVγE
-40 -30 -20 -10 0 10 20 30 400
50010001500200025003000350040004500
: 1.60σ: -1.82, µ 266-299 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
10000 : 2.24σ: -1.66, µ 299-332 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
100001200014000 : 3.85σ: -0.78, µ 332-365 MeVγE
-40 -30 -20 -10 0 10 20 30 400
50001000015000200002500030000
: 3.98σ: -0.09, µ 365-398 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
100001200014000160001800020000
: 3.89σ: 0.15, µ 398-431 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
100001200014000160001800020000 : 3.81σ: 0.32, µ 431-464 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
1000012000 : 3.69σ: 0.66, µ 464-497 MeVγE
-40 -30 -20 -10 0 10 20 30 400
2000400060008000
10000 : 3.64σ: 0.73, µ 497-530 MeVγE
-40 -30 -20 -10 0 10 20 30 400
100020003000400050006000700080009000 : 3.53σ: 0.85, µ 530-563 MeVγE
-40 -30 -20 -10 0 10 20 30 400
1000200030004000500060007000
: 3.48σ: 0.82, µ 563-596 MeVγE
-40 -30 -20 -10 0 10 20 30 400
50010001500200025003000350040004500 : 3.75σ: 0.99, µ 596-629 MeVγE
-40 -30 -20 -10 0 10 20 30 400
50010001500200025003000 : 3.88σ: 0.96, µ 629-662 MeVγE
-40 -30 -20 -10 0 10 20 30 400
5001000150020002500300035004000 : 3.70σ: 0.80, µ 662-695 MeVγE
-40 -30 -20 -10 0 10 20 30 400
500100015002000250030003500 : 3.96σ: 0.90, µ 695-728 MeVγE
[MeV]γE300 400 500 600 700
[d
eg]
θ ∆
-20-15-10-505
101520
energy dependent cut rangesenergy dependent cut ranges
[deg]recθ-calcθ-40 -30 -20 -10 0 10 20 30 40
#
0
2
4
6
8
10
12
14
16
310×: 3.70 [deg]σ 464-497 MeVγE
— butanol — scaled carbon — reconstructed hydrogen — fit function
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 29
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
cos θπ dependent selection - Theta for Eγ = (464− 497) MeV
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
200
400
600
0
200
400
600: 1.28σ: -2.77, µ < -0.89θ -1.00 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
0
500
1000
1500: 2.28σ: -1.53, µ < -0.56θ -0.67 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
2000
0
500
1000
1500
2000: 3.64σ: 0.50, µ < -0.22θ -0.33 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
0
500
1000
1500: 4.24σ: 1.01, µ < 0.11θ 0.00 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
200
400
0
200
400: 5.09σ: 2.55, µ < 0.44θ 0.33 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
510
15
20
0
510
15
20: 2.24σ: -3.00, µ < 0.78θ 0.67 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
0
500
1000: 1.47σ: -3.00, µ < -0.78θ -0.89 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
2000
0
500
1000
1500
2000: 2.58σ: 0.45, µ < -0.44θ -0.56 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
1000
2000
3000
0
1000
2000
3000: 2.77σ: 0.86, µ < -0.11θ -0.22 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
0
500
1000
1500: 3.91σ: 1.31, µ < 0.22θ 0.11 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
50
100
150
0
50
100
150: 8.44σ: 3.00, µ < 0.56θ 0.44 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
5
10
0
5
10: 0.59σ: -1.90, µ < 0.89θ 0.78 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
200
400
600
800
0
200
400
600
800: 1.99σ: -3.00, µ < -0.67θ -0.78 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
2000
0
500
1000
1500
2000: 3.22σ: 1.45, µ < -0.33θ -0.44 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
1000
2000
0
1000
2000: 3.55σ: 1.83, µ < -0.00θ -0.11 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
0
500
1000: 4.38σ: 2.09, µ < 0.33θ 0.22 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
20
40
0
20
40: 0.53σ: -1.72, µ < 0.67θ 0.56 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
2
4
0
2
4: 0.12σ: -1.10, µ < 1.00θ 0.89 < cos
πθcos -1 -0.5 0 0.5 1
[d
eg]
θ ∆
-20-15-10-505
101520
dependent cutπθcos
— butanol — scaled carbon — reconstructed hydrogen — fit functionKarsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 30
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
cos θπ dependent selection - Theta for Eγ = (464− 497) MeV
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
200
400
600
0
200
400
600: 1.28σ: -2.77, µ < -0.89θ -1.00 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
0
500
1000
1500: 2.28σ: -1.53, µ < -0.56θ -0.67 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
2000
0
500
1000
1500
2000: 3.64σ: 0.50, µ < -0.22θ -0.33 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
0
500
1000
1500: 4.24σ: 1.01, µ < 0.11θ 0.00 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
200
400
0
200
400: 5.09σ: 2.55, µ < 0.44θ 0.33 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
510
15
20
0
510
15
20: 2.24σ: -3.00, µ < 0.78θ 0.67 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
0
500
1000: 1.47σ: -3.00, µ < -0.78θ -0.89 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
2000
0
500
1000
1500
2000: 2.58σ: 0.45, µ < -0.44θ -0.56 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
1000
2000
3000
0
1000
2000
3000: 2.77σ: 0.86, µ < -0.11θ -0.22 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
0
500
1000
1500: 3.91σ: 1.31, µ < 0.22θ 0.11 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
50
100
150
0
50
100
150: 8.44σ: 3.00, µ < 0.56θ 0.44 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
5
10
0
5
10: 0.59σ: -1.90, µ < 0.89θ 0.78 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
200
400
600
800
0
200
400
600
800: 1.99σ: -3.00, µ < -0.67θ -0.78 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
1500
2000
0
500
1000
1500
2000: 3.22σ: 1.45, µ < -0.33θ -0.44 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
1000
2000
0
1000
2000: 3.55σ: 1.83, µ < -0.00θ -0.11 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
500
1000
0
500
1000: 4.38σ: 2.09, µ < 0.33θ 0.22 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
20
40
0
20
40: 0.53σ: -1.72, µ < 0.67θ 0.56 < cos
-40 -30 -20 -10 0 10 20 30 40
-40 -30 -20 -10 0 10 20 30 40
0
2
4
0
2
4: 0.12σ: -1.10, µ < 1.00θ 0.89 < cos
πθcos -1 -0.5 0 0.5 1
[d
eg]
θ ∆
-20-15-10-505
101520
dependent cutπθcos
[deg]pθ ∆-40 -30 -20 -10 0 10 20 30 40
#
0
1000
2000
3000: 2.82σ: 1.22, µ < -0.11θ -0.22 < cos
— butanol — scaled carbon — reconstructed hydrogen — fit functionKarsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 30
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Selected events
edge [MeV] event class 1 [×106] event class 2 [×104]
350 2.5 9.66450 1.7 56.43550 0.54 36.67660 0.13 15.14750 0.05 7.96
For eventclass 1 rougly 4.92 ×106 and for event class 2 rougly 1.26 ×106 reconstructedhydrogen events!
amount of background in event class 1
%
0
10
20
30
πθcos -1 -0.5 0 0.5 1
[M
eV]
γE
200
300
400
500
600
700
4.66 3.53 2.1 6.09 6.56 3.86 3.29 1.69 0.94 0.94 1.82 2.76 5.71 3.73 7.62 10.74 12.46 23.26
2.9 1.76 1.44 1.23 1.22 1.47 1.39 1.33 1.28 0.83 0.78 0.84 0.78 1.07 1.34 2.32 9.05 5.49
2.4 1.51 0.85 0.82 0.54 0.86 0.9 0.91 1.17 1.03 0.75 0.83 0.89 0.76 0.87 1.36 2.28 4.26
2.34 1.28 0.82 0.85 0.65 0.64 0.64 0.66 0.69 0.66 0.67 0.61 0.65 0.69 0.5 0.49 1.54 2.27
3.71 2.46 1.61 1.54 1.23 0.95 0.93 1.01 0.99 0.94 1.03 0.98 0.7 0.71 0.89 0.77 1.75 1.49
4.82 2.69 1.7 1.26 1.17 1.05 1.03 1.09 1.26 1.21 1.1 1.13 1.16 0.8 0.84 0.82 1.78 1.89
7.82 4.06 2.68 2.21 1.78 1.74 1.41 1.84 1.74 1.77 2.12 1.54 1.76 1.31 1.48 1 2.64 4.18
10.42 4.96 3.72 2.83 2.64 2.21 2.12 2.72 2.48 2.39 2.61 2.31 2.02 2.32 1.85 1.89 5.2 5.74
14.37 3.45 3.2 3.13 2.79 3.53 3.39 4.35 4.33 4.26 3.99 4.38 5.24 4.15 3.93 4.71 7.71 3.47
5.92 2.97 4.47 4.13 4.04 3.47 4.49 4.64 5.07 6.14 6.46 5.71 8.66 7.15 4.39 4.06 7.62 3.73
11.71 7.91 6.18 4.45 4 5.28 5.4 5.72 6.1 6.4 13.79 9.82 13.36 15.43 12.93 6.8 16.12 9.75
10.66 13.01 5.92 4.89 4.2 5.24 6.03 8.04 7.89 8.19 8.37 13.47 14.03 14.42 7.34 10.56 8.07 4.09
11.66 13.16 16.12 8.37 6.91 7.12 6.24 6.97 8.32 10.46 6.8 24.74 26.68 20.75 11.39 8.58 10 3.83
34.08 6.47 10.12 6.14 8.56 6.37 6.47 7.24 8.67 10.87 9.55 11.41 22.78 9.49 8.28 22.9 8.96 12.18
30.23 8.21 12.33 8.59 9.09 5.09 4.54 7.96 8.27 10.37 12.75 9.44 11.17 16.18 7.15 13.34 14.07 7.93
14.52 10.64 4.32 3.81 5.24 3.98 5.5 6.27 7.32 2.93 12.28 11.26 12.22 9.51 9.45 10.13 7.03 7.97
20 2.65 6.14 6.14 6 4.24 5.64 6.52 8.08 6.94 7.06 10.16 6.74 3.52 2.53 13.53 6.35 8.73
Overall background
P R E L I M I N A R Y %
regions with high background contribution!Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 31
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Selected events
edge [MeV] event class 1 [×106] event class 2 [×104]
350 2.5 9.66450 1.7 56.43550 0.54 36.67660 0.13 15.14750 0.05 7.96
For eventclass 1 rougly 4.92 ×106 and for event class 2 rougly 1.26 ×106 reconstructedhydrogen events!
amount of background in event class 2
%
0
2
4
6
8
10
πθcos -1 -0.5 0 0.5 1
[M
eV]
γE
300350400450500550600650700750
Overall background
0.11 0.12 1.21 0.23 0.17 0.1 0.2 0.82 2.71 3.27 5.34 5.72 34.42 12.62 27.16 30.24 33.56 29.25
0.16 0.05 0.25 0.13 0.05 0.03 0.04 0.06 0.15 0.26 1.54 2.59 7.94 7.02 9 39.12 57.21 30.09
0.11 0.06 0.19 0.07 0.05 0.04 0.06 0.03 0.12 0.08 0.3 1.42 2.68 3.73 6.62 8.72 42.07 74.12
0.26 0.14 0.25 0.11 0.03 0.09 0.06 0.04 0.05 0.08 0.07 0.25 1.8 2.36 5.07 12.07 48.62 21.36
0.53 0.18 0.21 0.11 0.18 0.09 0.09 0.11 0.09 0.1 0.09 0.25 0.54 1.75 2.11 7.41 47.9 69.28
0.78 0.28 0.27 0.15 0.19 0.15 0.26 0.2 0.14 0.19 0.15 0.18 0.33 1.01 5.44 4.75 52.02 31.16
0.91 0.1 0.42 0.32 0.27 0.18 0.21 0.28 0.22 0.17 0.3 0.3 0.26 0.42 2.24 6.3 47.12 44.3
1.79 0.68 0.65 0.4 0.29 0.23 0.23 0.25 0.18 0.26 0.11 0.21 0.09 0.33 2.51 8.51 29.99 65.88
2.26 0.6 0.36 0.4 0.15 0.29 0.28 0.12 0.29 0.48 0.21 0.29 0.22 0.35 2.82 3.94 14.44 31.45
2.75 1.28 1.31 0.74 0.6 0.19 0.67 0.41 0.21 0.23 0.27 0.6 1.18 0.26 0.67 19.96 60.03 57.44
1.05 1 1.52 1.03 0.55 0.71 0.56 0.42 0.37 1.04 0.99 0.97 1.35 0.72 0.38 11.82 80.49 24.34
2.14 0.52 1.36 0.77 0.7 0.74 0.66 0.63 0.82 0.41 0.85 0.9 0.28 1.76 0.56 5.06 58.84 29.64
2.27 0.9 1.23 1.18 0.36 0.29 0.59 0.6 0.38 1.12 1.59 0.57 1.16 1.73 1.95 3.33 123.36 124.85
1.53 1.16 1.56 1.77 0.93 0.66 0.51 1.01 0.56 0.7 0.81 0.75 1.5 1 1.22 7.79 48 0.08
P R E L I M I N A R Y %
regions with very few statistic!Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 31
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
dE over E cuts (CB and PID) -Additional cuts
[MeV]CBdepE
0 50 100 150 200 250 300 350 400
[M
eV]
PID
dep
E∆
0
1
2
3
4
5
6
7
8
9
10
1
10
210
310
410
[MeV]CBdepE
0 50 100 150 200 250 300 350 400
[M
eV]
PID
dep
E∆
0
1
2
3
4
5
6
7
8
9
10
1
10
210
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 32
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
dE over E cuts (TAPS and VETOs) -Additional cuts
[MeV]TAPSdepE
0 50 100 150 200 250 300 350 400
[M
eV]
VE
TO
dep
E∆
0
1
2
3
4
5
6
7
8
9
10
1
10
210
310
[MeV]TAPSdepE
0 50 100 150 200 250 300 350 400
[M
eV]
VE
TO
dep
E∆
0
1
2
3
4
5
6
7
8
9
10
-110
1
10
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 33
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Acceptance ε
[MeV]γE300 400 500 600 700 800
πθco
s
-1-0.8-0.6-0.4-0.2
00.20.40.60.8
1
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
[MeV]γE400 600 800 1000 1200 1400
π2θco
s
-1-0.8-0.6-0.4-0.2
00.20.40.60.8
1
0
0.1
0.2
0.3
0.4
0.5
ε =Nrec
Ngen
(cos θπ,Eγ
)
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 34
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Determination through differences
• Different settings can be combined in such a way that only terms including ΣB or Gremain
→ f (θ, φ) = A sin 2φ with A = −δl ΣB
→ g(θ, φ) = B cos 2φ with B = Dδl ΛzG
Combination of φ-asymmetries for different settingsEγ = (464-497) MeV and−0.22 < cos θπ ≤ −0.11
[deg]πφ -150 -100 -50 0 50 100 150
-0.5-0.4-0.3-0.2-0.1
00.10.20.30.40.5
φ-asymmetry for ΣB
[deg]πφ -150 -100 -50 0 50 100 150
-0.5-0.4-0.3-0.2-0.1
00.10.20.30.40.5
φ-asymmetry for G
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 35
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Frozen-spin butanol target
Dynamic Nuclear Polarization
1 butanol target is doped with paramagnetic radicals
2 electrons polarized with a 2.5 T magnetic field at a temperature of 1K
3 electron polarization can be transferred to the nucleons by microwave irradiation
4 ”freeze” the spin (≈ 25mK ) and combine it with a holding coil→ long relaxation time
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 36
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Linearly polarized photons
• Incoherent bremsstrahlung: only one single atom of the crystal absorbs the recoilingmomentum ~q → no preferred plane between incoming electron and outgoing photon→ no favored orientation of the electric field vector of the photon→ no polarizedphotons
• Coherent bremsstrahlung: if ~q = n~g with ~g =3∑
i=1
~bi · hi → single atoms can interfere
constructively!→ preferred plane between incoming electron and outgoing photon→orientation of the field vector of the photon→ polarized photons
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 37
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Circularly polarized photons
• Mott-scattering: electrons in gold (Z=79) interact via spin-orbit coupling with thelongitudinally polarized electrons from MAMI→ asymmetry in backscattering!→polarization degree of electrons
• helicity transfer from electrons to photons→ circularly polarized photons
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 38
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Illustrative presentation of the beam asymmetry Σ
~L = orbital angular momentum of baryon (B) and meson (M)~S = spin of baryon~E = electric field~B = magnetic field
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 39
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Ambiguity studies - Comparison MAID- and BnGA-PWA
overall solution, without P11(1770), without D15(1560)
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 40
Appendix Helmholtz-Institut für Strahlen- und Kernphysik
Resonances
1 bump in the cross section
2 maximum in imaginary part of the multipole and zero-crossing in real part! (Problem:not unambiguous due to background)
3 Solution: scattering amplitude solution can be expanded into the complex energyplane
• E → E = ER + EI• ”mass” of a resonance = real part of the pole position• ”width” of a resonance = imaginary part via Γ = −2ImE
Karsten Spieker Measurement of the double polarization observables G in pion photoproduction off the proton - September 21th, 2015 41