Photon Polarization AnalysisBill Bugg

Data selection:1) PCALE Max cut <4002) Visual Inspection. For every cycle of every run we plot

and examine a series of 72 histograms and scatter plots of signals from individual counters.PCALE,D,C,BAg1SicAg2SicAg1Ag2GCALCsI (channel 9)Toroid >50 ADC counts Possi TL,TR,BL,BR X,Y, collimator counters, etc.We look for changes in toroid current, or beam position, saturated channels, missed undulator pulses during the cycle and eliminate cycles on this basis.

3) Adjacent runs with opposite field are treated in pairs to obtain the global asymmetry.

I choose not to remove ‘flyers’(results outside 3 sigma) unless study of data for the cycles involved identifies a problemmissed earlier. The photon results are not sensitive to this choice.

4) In addition to the plots for each run cycle we write out file with mean, rms and number of events passing the tests for 18 elements. These are:

Ag1SiC, Ag2SiC, Ag1, Ag2, GcaL Possi Sum(4 quadrants), Toroid, Possi old, PcalE, D, C, x(bpm 6130), y(bpm 6130), and 4 collimator counters(ColT, ColB, ColR, ColL). These are recorded both for Undulator on and off. These data are written into an Excel file for processing and study and asymmetriy results passed to PAW for final fits.

5) Processed Excel files are available for all the September data so that anyone interested can play with the data. These files are my working files so you will find them full of a variety of plots and correlations which you can ignore if you wish.

ANALYSISIn routine analysis we use the means for each cycle. Background is subtracted and counter data normalized to AG1SiC signal. (Ag1 works about as well) . Normalization to toroid signal gives poorer results, Normalized signals and the difference/sum value evaluated are for each pair.

For target in data we also evaluate asymmetries for CsI central channel We also look at Possisum which should show no asymmetry. The results are fit by PAW

An example follows of output looked at for each cycle (same cycle I showed in Princeton. I was too lazy to make new slides)

Run 2542 target inGood

Run 2590 cycle 1Target out (Bad)

Run 1571 saturation of Ag2Sic(bad)

Analysis has been completed for all the September data for target in and target out and Spectrometer currents 100, 120, 140, 160positrons, 160electrons, 180 normal fluid and 180 ferro fluid. There is no a priori reason to expect the photon results to depend on spectrometer current but we present them separately for comparison as some differences in errors show up.

Data for Spectrometer current = 100 are shown as an example

ag2sic-

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103 109 115 121 127 133 139 145 151 157 163 169 175 181 187 193 199 205

ag2sic-

gcal-

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136 141 146 151 156 161 166 171 176 181 186 191 196 201 206

gcal-

ag2-

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136 141 146 151 156 161 166 171 176 181 186 191 196 201 206

ag2-

Asymmetry Photon September data Spectrometer=100

ag2sic+

-0.15

-0.1

-0.05

0

0.05

0.1

1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103 109 115 121 127 133 139 145 151 157 163 169 175 181 187 193 199 205ag2sic+

CsI-

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136 141 146 151 156 161 166 171 176 181 186 191 196 201 206

CsI-

Possi-

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136 141 146 151 156 161 166 171 176 181 186 191 196 201 206Possi-

Positron data

Asymmetry

Spect ag2sic- ag2sic+ gcal- gcal+ ag2- ag2+

100 0.0385 -0.0359 0.0383 -0.0390.040

1-

0.0383

120 0.0407 -0.0366 0.0364-

0.03390.038

7-

0.0361

140 0.0395 -0.0323 0.0322-

0.0342 0.034-

0.0345

160p 0.0359 -0.0384 0.0282-

0.03450.025

4 -0.021

160e 0.0367 -0.0326 0.0382-

0.03790.014

7-

0.0273

180 0.0372 -0.0475 0.0413-

0.02360.031

9-

0.0291

out 0.0403 -0.0249 0.0384-

0.0257 0.263-

0.0137

% error

100 2.5455 3.5097 3.4987 3.871814.66

3 16.188

120 3.2924 4.9454 6.044 7.020635.91

7 13.767

140 6.6582 7.4923 3.882 6.286517.64

7 16.464

160p 8.6351 16.042 12.199 17.68147.63

8 81.905

160e 13.433 10.675 23.796 23.509112.2

4 80.586

180 17.043 24 18.983 42.37340.12

5 34.124

out 4.472 1562.2 14.115 96.8876.806

1 237.96

ag2sic-

0.033

0.034

0.035

0.036

0.037

0.038

0.039

0.04

0.041

0.042

100 120 140 160p 160e 180 out

ag2sic-

gcal-

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

100 120 140 160p 160e 180 out

gcal-

ag2-

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

100 120 140 160p 160e 180 out

ag2-

Asymmetry

ag2sic-

0

2

4

6

8

10

12

14

16

18

100 120 140 160p 160e 180 out

ag2sic-

gcal-

0

5

10

15

20

25

100 120 140 160p 160e 180 out

gcal-

ag2-

0

20

40

60

80

100

120

100 120 140 160p 160e 180 out

ag2-

% error

Asymmetry %Target outweighted mean %error

ag2sic 3.531473 0.051825ag2 2.683052 0.155043gcal 3.967002 0.059846

0.25X0 Target Inweighted mean % error

ag2sic 3.679762 0.071897ag2 3.499242 0.072967gcal 3.623144 0.046247CsI 1.187983 0.13398

June data Spectrometer=140

Conclusions• Photon Asymmetry is well measured in all 3 counters

• Best measurement with Ag2SiC, then Gcal followed by Ag2

• Measurements are consistent with having same asymmetry within errors independent of spectrometer current.

• Errors in each counter increases with spectrometer current( or more probably in my opinion due to data quality deterioration as run progressed)

Comments• Transmission is very different from June• Positrons strike almost entirely the left hand side

of exit window• Positrons (and electrons) pass primarily through

the downstream half of jaw slit.• Beam is consistently steered to left of gamma

collimator aperture. Steering is different for undulator on/off

• Undulator steers the electron beam about 25 microns in x and y when it fires (bpm 6130)

0

0.5

1

1.5

2

2.5

3

3.5

0 50 100 150 200 250

ratio top/bot sig

ratio left/right sig

0

2

4

6

8

10

12

0 50 100 150 200 250

top/bot back

left/right back

Spect=100 data

Undulator Steering delta x(mm) Undulator off -undulator on

-6.00E-02

-5.00E-02

-4.00E-02

-3.00E-02

-2.00E-02

-1.00E-02

0.00E+00

0 5 10 15 20 25 30

Run Index

De

lta

x b

pm

61

30

(m

m)

Series1

Delta y (mm) Und off minus on

-9.00E-02

-8.00E-02

-7.00E-02

-6.00E-02

-5.00E-02

-4.00E-02

-3.00E-02

-2.00E-02

-1.00E-02

0.00E+00

0 5 10 15 20 25

Run Index

De

lta

y(m

m)

0.-04628402