[Frost] Moeller measurements for g9a

[Eugene Pasyuk]

There was some incorrect handling of beam charge asymmetry correction in 
Moeller measurements at the beginning. For that reason we always did two 
measurement with opposite Moeller target polarization.
If you take an average of the two without sign, the it cancels that 
problem.  Uncertainties shown there are statistical only. Sytematics of 
our Moeller polarimeter is believed to be between 2 and 3%
If you do this average, than you will see that all three pairs of 
measurements are consistent with each other within their uncertainties. 
For the first pair it is 81.9%, for the second one it is 83.9 and for 
the third one it is 84.4%

-Eugene

Michael Dugger wrote, On 03/09/11 18:23:
>
> Hi,
>
> It looks like there are potential problems with some of the Moeller
> measurements.
>
> Run 55544:
> We have 4 measurements taken over a 14 minute time period with
> P = 85.228 +/- 1.42
> P = -78.523 +/- 1.35
> P = -79.150 +/- 1.26
> P = 88.700 +/- 1.48
>
> There is a large change between the polarization values (>  10%). The Two
> negative measurements are much lower than is typical and I want to take
> these out of the average. Is there a reason not to remove these negative
> measurements?
>
> Run 55552:
> We have 2 measurements:
> P = 84.167 +/- 1.33
> P = -84.725 +/- 1.53
>
> The first measurement had True Rates = 0.00 and Accidental Rates = 0.00,
> also the SLM Current = 0.125 (whereas most all other runs had SLM
> Current ~ 6). The second measurement had True Rates = 1002.00 and
> Accidental Rates = 3.50, with SLM Current = 1.192. (Typically the True
> Rate is about 6000). Moreover, 2C21 X = 0.0 (-4.455) and 2C21 Y = 0.0
> (1.560) for the first (second) measurement.  I think that the Moeller
> measurements for run 55552 are highly suspect and should be thrown out of
> the determination of the polarization average.
>
> Additional question: How important are the 2C21 X and Y values for the
> Moeller measurement?
>
> Take care,
> Michael
>
> _______________________________________________
> Frost mailing list
> Frost at jlab.org
> https://mailman.jlab.org/mailman/listinfo/frost