Difference between revisions of "Final analysis"
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88.92 +/- 0.04 (stat) +/- 1.12 (sys) % | 88.92 +/- 0.04 (stat) +/- 1.12 (sys) % | ||
| − | =Compton= | + | ==Compton== |
Mindy's HAPLOG post: | Mindy's HAPLOG post: | ||
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http://www.jlab.org/~riordan/20110412/Compton_slugBP_PREx-I_Apr_2011.gif | http://www.jlab.org/~riordan/20110412/Compton_slugBP_PREx-I_Apr_2011.gif | ||
| − | ==Systematic Error== | + | ===Systematic Error=== |
{| class="wikitable" | {| class="wikitable" | ||
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|} | |} | ||
| − | + | Systematic Error Notes | |
*From Megan over gain shift: | *From Megan over gain shift: | ||
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analyzing power = 0.018299996 +- 0.00002583 (sta.) +- 0.000279099 (sys.) | analyzing power = 0.018299996 +- 0.00002583 (sta.) +- 0.000279099 (sys.) | ||
| − | =Moller= | + | ==Moller== |
http://www.jlab.org/~moller/e02-006.html | http://www.jlab.org/~moller/e02-006.html | ||
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http://www.jlab.org/~riordan/20110412/mollerpull_20110412.png | http://www.jlab.org/~riordan/20110412/mollerpull_20110412.png | ||
| − | ==Systematic Error== | + | ===Systematic Error=== |
Sasha's report at the Jan 2011 collaboration meeting | Sasha's report at the Jan 2011 collaboration meeting | ||
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| 1.12 | | 1.12 | ||
|} | |} | ||
| + | |||
| + | =Finite Acceptance= | ||
| + | |||
| + | The radiative tail leads to an effective drop in the measured Q^2 by 0.68% | ||
| + | |||
| + | *http://ace.phys.virginia.edu:8080/HAPPEX/2573 | ||
| + | |||
| + | =Background= | ||
| + | |||
| + | ==Inelastic== | ||
| + | |||
| + | See Kiad's presentation | ||
| + | |||
| + | http://ace.phys.virginia.edu:8080/HAPPEX/2553 | ||
| + | |||
| + | The acceptance for the first excited state of Pb is <0.1%. It's expected to have an asymmetry ~1.3 of the elastic asymmetry so it is totally negligable. | ||
| + | |||
| + | The first excited state of carbon is outside our acceptance and does not contribute | ||
| + | |||
| + | ==Carbon== | ||
| + | |||
| + | In progress | ||
| + | |||
| + | ==Rescattering== | ||
| + | |||
| + | In progress | ||
| + | |||
| + | =Nonlinearity= | ||
Revision as of 13:31, 12 April 2011
Polarimetry
Compton
87.41 +/- 0.12 (stat) +/- 1.51 (sys) %
Moller
88.92 +/- 0.04 (stat) +/- 1.12 (sys) %
Compton
Mindy's HAPLOG post:
http://ace.phys.virginia.edu:8080/HAPPEX/2582
Final result: 87.41 +/- 0.12 (stat) +/- 1.51 (sys) % (??)
chi^2/NDoF = 1.09 for 13 points over the experiment
http://www.jlab.org/~riordan/20110412/Compton_slugBP_PREx-I_Apr_2011.gif
Systematic Error
| Rel Uncer. (%) | |||
|---|---|---|---|
| Laser Pol. | 0.07 | http://ace.phys.virginia.edu:8080/HAPPEX/2530 | |
| Gain shift | 1.3 | email from Megan Friend, see below | |
| Collimator Pos. | 0.02 | http://ace.phys.virginia.edu:8080/HAPPEX/2568 | |
| Nonlinearity | 0.3 | http://ace.phys.virginia.edu:8080/HAPPEX/2569 | |
| TOTAL |
Systematic Error Notes
- From Megan over gain shift:
I don't think I'm going to be able to get a number for the gain shift during PREX, although it should scale linearly with signal-background size. Using the 1% gain shift we saw during HAPPEX (signal+bkg to background = 122e6 to 53e6), that would give us a 0.8% gain shift for PREX (signal+bkg to background = 48e6 to 30e6 at 1kHz * 3.3 to convert to 30Hz). This would give us a change in the final polarization number of 1.3%, if it's folded into the background subtraction ( which comes from comparing a background subtraction of (48e6-30e6*(1.008))/(48e6-30e6) ). So I'd say the possible gain shift gives you a 1.3% systematic error.
- From Megan over radiative correction:
I just ran through the PREX data to add in a radiative correction, and I get that this increases the analyzing power by 0.3% (from 0.01828903 to 0.01834393). This is consistent with what I've seen, so I think it's safe to add that in there.
There is an increase in analyzing power of 0.3%, which corresponds to a decrease in beam polarization by 0.3%. Therefore, the final analyzing power should multiply by (1+0.003) due to A_real = A_exp * (1+0.3%)
w/o the radiative correction:
analyzing power = 0.01824526 +- 0.00002583 (sta.) +- 0.000279099 (sys.)
w/ the radiative correction:
analyzing power = 0.018299996 +- 0.00002583 (sta.) +- 0.000279099 (sys.)
Moller
http://www.jlab.org/~moller/e02-006.html
Final result weighted average: 88.92 +/- 0.04 (stat) +/- 1.12 (sys) %
(not sure if the systematic is relative or absolute)
The first measurement of the set is much lower than the others
http://www.jlab.org/~riordan/20110412/mollerpull_20110412.png
Systematic Error
Sasha's report at the Jan 2011 collaboration meeting
| Uncer. (%) | |
|---|---|
| Fe Pol. | 0.25 |
| Targ Discrep. | 0.5 |
| Targ Saturation | 0.3 |
| Analyzing power | 0.3 |
| Levchuk | 0.5 |
| Targ temp | 0.02 |
| Dead time | 0.3 |
| Background | 0.3 |
| Others | 0.5 |
| Current diff | 0.3 |
| TOTAL | 1.12 |
Finite Acceptance
The radiative tail leads to an effective drop in the measured Q^2 by 0.68%
Background
Inelastic
See Kiad's presentation
http://ace.phys.virginia.edu:8080/HAPPEX/2553
The acceptance for the first excited state of Pb is <0.1%. It's expected to have an asymmetry ~1.3 of the elastic asymmetry so it is totally negligable.
The first excited state of carbon is outside our acceptance and does not contribute
Carbon
In progress
Rescattering
In progress
