[Frost] Moeller measurements for g9a

[Michael Dugger]

Eugene,

Why bother making the measurement at all. It sounds like a waste of time.

If the Moeller measurements are important then we have something to argue 
about. If you take the position that the measurements don't matter, then 
what can I say?

I'm getting close to normalizing the polarization to the eta 1525 MeV 
measurement. Perhaps there is nothing to discuss.

Take care,
Michael


On Thu, 10 Mar 2011, Eugene Pasyuk wrote:

> I don't think anything is wrong with measurements. Our measurements were
> consistent with other halls with given linac energy, Wien angle setting
> and Mott measurements in the injector.
> If there are no changes in the accelerator configuration thera no
> reasons for beam polarization to change. There are a few parameters that
> may affect polarization: linac energy, Wien angle and there is some
> correlation with quantum efficiency of the photo cathode.
> The first two were kept constant for given accelerator energy. The
> energy also was constant within certain periods when we intentionally
> changed it. We always did Moeller measurements after they did spot move
> on the cathode or any other changes that may affect polarization.
>
>
> -Eugene
>
> Michael Dugger wrote, On 03/10/11 00:28:
>>
>> Eugene,
>>
>> We have three Moeller measurements that do not have a +/- pair. The runs
>> lacking the pairwise measurements are: 55608, 56194, and 56202. It looks
>> like these Moeller measurements need to be thrown out.
>>
>> I still think that the Moeller measurement for run 55552 is probably
>> garbage. I do not see how that measurement can be trusted.
>>
>> -Michael
>>
>>
>>
>> On Thu, 10 Mar 2011, Eugene Pasyuk wrote:
>>
>>> 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
>>>>
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