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Measurement of the double polarization observables G in pion photoproduction off the proton Karsten Spieker Helmholtz-Institut für Strahlen- und Kernphysik University of Bonn, Germany September 21th, 2015

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Page 1: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 2: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 3: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 4: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 5: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 6: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 7: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 8: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 9: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 10: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 11: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 12: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

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

Page 13: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 14: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 15: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 16: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 17: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 18: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 19: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 20: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 21: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 22: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 23: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

Page 36: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

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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

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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

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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

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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

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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

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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

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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

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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

Page 45: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

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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

Page 47: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 48: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 49: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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

Page 50: Measurement of the double polarization observables G in ...theorie.ikp.physik.tu-darmstadt.de/erice/2015/sec/talks/monday/spieker.pdfMeasurement of the double polarization observables

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