Cross Sections, Γγγ’s, and uncertainties for12C and 208Pb

Dustin McNultyUMass

PrimEx Collaborationmcnulty@jlab.org

July 21, 2007

PrimEx Collaboration Jefferson Lab Hall B

12C Yield

(degrees)θ Production Angle, 0π0 0.5 1 1.5 2 2.5 3

)o Y

ield

(per

0.0

20 π

0

0.2

0.4

0.6

0.8

1

1.2

310× C, crystal only)12 Photoproduction Yield (0π

yield + bkgd0πElastic

bkgd0πInelastic s = 97330πTotal

]= 289os:[0,0.30π

Preliminaryelastic range:[0.906,1.086]

(degrees)θ Production Angle, 0π0 0.5 1 1.5 2 2.5 3

’sγ/2

.334

e+12

inci

dent

o

Yie

ld/0

.02

0 π

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1310× C, crystal only)12 Photoproduction Yield (0π

yield0πElastic s = 640040πTotal

]= 5187os:[0,0.30π

Preliminaryelastic range:[0.906,1.086]

.

Dustin McNulty, Collaboration Meeting, July 21, 2007 1

PrimEx Collaboration Jefferson Lab Hall B

12C Efficiencies

Losses (%)

Description 12C

ROC Fastbus Errors 0 �448�

0 �009

Photon Absorption in Target 5 �41

�

0 �02

Best (tdiff) Candidate selection 2 �5 �

0 �3Elasticity Cut:

�

0 �906 � 1 �086�

1 �7 �

0 �3Veto Cut: all flags

�0 � 1 � 2 � 3 �

1 �97

�

0 �12

Branching Ratio π0 � γγ 1 �2 �

0 �03

Total 13 �25

�

0 �4

Table 1: Summary of non-geometric losses.

Dustin McNulty, Collaboration Meeting, July 21, 2007 2

PrimEx Collaboration Jefferson Lab Hall B

Yield Fit for 12C

(degrees)θ Production Angle, 0π0 0.5 1 1.5 2 2.5 3 3.5 4

(degrees)θ Production Angle, 0π0 0.5 1 1.5 2 2.5 3 3.5 4

o Y

ield

/0.0

20 π

0

100

200

300

400

500

600

700

800

900

C, crystal only)12 Photoproduction yield (0π

yield0π Measured •

yield Fit0π------ Calculated

Fit Parameters: 0.0586 ± : 1.910 ncb

0.1584 eV± : 8.246 pb

0.047 rad.±| : 0.9908 φ| 0.398± : 7.2359 bb

/ndf : 190.56 / 1472χ

Preliminary----- Primakoff

----- Nuclear Coherent----- Interference----- Incoherent

.

Dustin McNulty, Collaboration Meeting, July 21, 2007 3

PrimEx Collaboration Jefferson Lab Hall B

208Pb Yield

(degrees)θ Production Angle, 0π0 0.5 1 1.5 2 2.5

)o Y

ield

(per

0.0

20 π

0

100

200

300

400

500

600

700

800Pb, crystal only)208 Photoproduction Yield (0π

yield + bkgd0πElastic

bkgd0πInelastic s = 6610πTotal

]= 75os:[0,0.30π

Preliminaryelastic range:[0.906,1.086]

(degrees)θ Production Angle, 0π0 0.5 1 1.5 2 2.5

’sγ/1

.311

e+12

inci

dent

o

Yie

ld/0

.02

0 π

0

100

200

300

400

500

600

700

800Pb, crystal only)208 Photoproduction Yield (0π

yield0πElastic s = 84430πTotal

]= 4624os:[0,0.30π

Preliminaryelastic range:[0.906,1.086]

.

Dustin McNulty, Collaboration Meeting, July 21, 2007 4

PrimEx Collaboration Jefferson Lab Hall B

208Pb Efficiencies

Losses (%)

Description 208Pb

ROC Fastbus Errors 0 �468�

0 �013

Photon Absorption in Target 5 �92

�

0 �01

Best (tdiff) Candidate selection 1 �1 �

0 �3Elasticity Cut:

�

0 �906 � 1 �086�

1 �7 �

0 �3Veto Cut: all flags

�0 � 1 � 2 � 3 �

1 �97

�

0 �12

Branching Ratio π0 � γγ 1 �2 �

0 �03

Total 12 �34

�

0 �4

Table 2: Summary of non-geometric losses.

Dustin McNulty, Collaboration Meeting, July 21, 2007 5

PrimEx Collaboration Jefferson Lab Hall B

Yield Fit for 208Pb

(degrees)θ Production Angle, 0π0 0.5 1 1.5 2 2.5 3

(degrees)θ Production Angle, 0π0 0.5 1 1.5 2 2.5 3

o Y

ield

/0.0

20 π

0

100

200

300

400

500

Pb, crystal only)208 Photoproduction yield (0π

yield0π Measured •

yield Fit0π------ Calculated

Fit Parameters: 0.0741 ± : 0.831 ncb

0.1646 eV± : 8.263 pb

0.120 rad.±| : 0.9388 φ| 0.492± : 7.6453 bb

/ndf : 168.83 / 1472χ

Preliminary----- Primakoff

----- Nuclear Coherent----- Interference----- Incoherent

.

Dustin McNulty, Collaboration Meeting, July 21, 2007 6

PrimEx Collaboration Jefferson Lab Hall B

Nuc. Coherent Parameter vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

ncY

ield

Fit

Par

amet

er: b

1.5

1.6

1.7

1.8

1.9

2

2.1

2.2

2.3

2.4

2.5C, crystal only)12Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

0.000±0.00

0.073±1.87

0.000±0.00

C, crystal only)12Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 7

PrimEx Collaboration Jefferson Lab Hall B

Incoherent Parameter vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

bY

ield

Fit

Par

amet

er: b

0

1

2

3

4

5

6

7

8

9

10C, crystal only)12Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

0.000±0.000.178±7.320.000±0.00

C, crystal only)12Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 8

PrimEx Collaboration Jefferson Lab Hall B

φ Parameter vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

(rad

)φ

Yie

ld F

it P

aram

eter

:

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1C, crystal only)12Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

0.000±0.00

0.024±0.970.000±0.00

C, crystal only)12Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 9

PrimEx Collaboration Jefferson Lab Hall B

Fit χ2/d.o.f vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

/Ndf

2 χY

ield

Fit

Par

amet

er:

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2C, crystal only)12Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

-0.000±0.00

0.404±1.09-0.000±0.00

C, crystal only)12Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 10

PrimEx Collaboration Jefferson Lab Hall B

Γγγ Parameter vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

(MeV

)γγΓ

Yie

ld F

it P

aram

eter

:

7.4

7.6

7.8

8

8.2

8.4

8.6

8.8-610×

C, crystal only)12Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

0.0000±0.0000.1758±8.206

0.0000±0.000

C, crystal only)12Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 11

PrimEx Collaboration Jefferson Lab Hall B

Nuc. Coherent Parameter vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

ncY

ield

Fit

Par

amet

er: b

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5Pb, crystal only)208Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

nan±nan

nan±nan

0.000±0.00

Pb, crystal only)208Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 12

PrimEx Collaboration Jefferson Lab Hall B

Incoherent Parameter vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

bY

ield

Fit

Par

amet

er: b

0

1

2

3

4

5

6

7

8

9

10Pb, crystal only)208Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

nan±nan0.496±5.510.000±0.00

Pb, crystal only)208Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 13

PrimEx Collaboration Jefferson Lab Hall B

φ Parameter vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

(rad

)φ

Yie

ld F

it P

aram

eter

:

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1Pb, crystal only)208Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

nan±nan

0.081±0.92 nan±nan

Pb, crystal only)208Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 14

PrimEx Collaboration Jefferson Lab Hall B

Fit χ2/d.o.f vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

/Ndf

2 χY

ield

Fit

Par

amet

er:

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2Pb, crystal only)208Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

0.000±0.00

0.491±1.250.000±0.00

Pb, crystal only)208Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 15

PrimEx Collaboration Jefferson Lab Hall B

Γγγ Parameter vs. Elasticty Cut and Fit Range

)σ ±Elasticity Cut (0 1 2 3 4 5 6 7 8 9 10

(MeV

)γγΓ

Yie

ld F

it P

aram

eter

:

7.4

7.6

7.8

8

8.2

8.4

8.6

8.8-610× Pb, crystal only)208Elasticity cut Systematic Error Study (

max fit0πθ o2.00

max fit0πθ o2.25

max fit0πθ o2.50

max fit0πθ o2.75

max fit0πθ o3.00

1.0k2.0k2.5k

0.0000±0.0000.0933±8.111

0.0000±0.000

Pb, crystal only)208Elasticity cut Systematic Error Study (

Dustin McNulty, Collaboration Meeting, July 21, 2007 16

PrimEx Collaboration Jefferson Lab Hall B

Systematic Error Table

Dustin McNulty, Collaboration Meeting, July 21, 2007 17

PrimEx Collaboration Jefferson Lab Hall B

Uncertainty (%)

Description 12C 208Pb

mγγ fits + inelast bkgd corr. 1.8 1.1

Photon flux 1.1 1.1

Nuclear coh. XS energy dep. 0.04�

0.04

�

Detection/Recon efficiency 0.5 0.5

Fiducial Acceptance 0.6 0.6

�

Event Selection 1.0 1.0

�

Target thick. + branch ratio 0.06 0.5

Tagged Photon Energy 0.3 0.3

�

Total 2.4 2.1

Table 3: Preliminary summary of systematic uncertainties.

� � Not beenre-evaluated yet.

Dustin McNulty, Collaboration Meeting, July 21, 2007 18

PrimEx Collaboration Jefferson Lab Hall B

Preliminary Result Summary

From 12C:Γπ0 γγ

� 8 �20eV

�

1 �8%

�

stat

� �

2 �4%

�

syst

� �1 �3

�%

�

model

�

From 208Pb:Γπ0 γγ

� 8 �11eV

�

2 �0%

�

stat

� �

2 �1%�

syst� �

1 �3

�

%

�

model

�

� � � � Not been fully evaluated.Above width results for Sergey’s incoherent XSparameterization

Dustin McNulty, Collaboration Meeting, July 21, 2007 19