Moller Measurements for GEP(II), Nov-Dec 2000
Because of the injector confuguration during this period, the leak from the the Hall C laser could produce polarization shifts of about 6%. In the last measurement of this period (#5) the polarization was measured with the other lasers turned off, and also the contribution from Hall C laser was measured. The results look consistent: at 500nA Hall C laser contributed about 3% of the Moller counting rate and diluted the polarization by about 6%. In the previous measurement (#4) the Hall C counting rate contribution was measured, while for the other measurements the contributions are unknown. Accordingly to the log files the Hall C laser was on during these measurements.
The measurement #5 does not need to be corrected for the leak. The measurement #4 has been corrected for a leak estimated during this measurement, by 4.4%. The other measurements have not been corrected. One may assume that the correction needed is 6% for all the measurement except the #5.
The Moller results, along with results from Compton polarimeter (obtained from the Compton polarimeter page), are presented on a plot.
The Compton results were averaged for 3 periods and are included in the following table:
# m d h Moller Moller corr by 6% Compton
for laser leak
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1 11 15 15 69.1 +/- 0.2 73.2 +/- 0.2 70.8 +/- 0.1
2 11 17 13 67.8 +/- 0.2 71.9 +/- 0.2
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3 12 01 15 72.2 +/- 0.2 76.5 +/- 0.2 76.1 +/- 0.1
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4 12 13 22 68.7 +/- 0.2 69.8 +/- 0.2 72.2 +/- 0.1
5 12 18 16 71.6 +/- 0.2 71.6 +/- 0.2
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The errors are statistical only.
For the measurement #5 (no error beacause of the leak) the Moller result is 0.8% below the Compton result.