[Frost] target polarization

[mcandrew at jlab.org]

Hi all,

Back in October I looked again at the NMR data to check the signs of the
target polarisation in the run table.

For what it's worth, here's my Wiki page summarising this investigation
and tables showing what I believe the target polarisation should be for
all runs:

http://clasweb.jlab.org/rungroups/g9/wiki/index.php/Checking_Target_Polarisation

Hope this helps!

Jo.

>
> Hi,
>
> Is there a general agreement within FROST that we use the helicity
> assignments given at the bottom of the Helicity assignment web page at
> http://clasweb.jlab.org/rungroups/g9/wiki/index.php/Helicity_assignment_for_g9a
> ?
>
> Is anyone using helicity assignments different than those given by
> Steffen?
>
> I think we should be clear as to what values everyone should use.
>
> Thanks for your time.
>
> Take care,
> Michael
>
> On Thu, 27 Jan 2011, Steffen Strauch wrote:
>
>> Dear Michael,
>>
>> The statistics of the pi+N data is good enough to look at the
>> asymmetries run-by-run.  That all runs give consistent results of the
>> experimental asymmetry despite different target polarizations, target
>> field settings, and half-wave plate configurations, except for all runs
>> with 1.645 GeV beam energy, hints in my opinion at a difference between
>> the status of the helicity bit and the actual beam helicity in the hall
>> for the two electron beam energies.
>>
>> I discussed this some time ago with Stepan and he mentioned that "it is
>> not uncommon that definition of the helicity bit changes with changes in
>> injector."  I was hoping the Moeller runs would allow to give a unique
>> correlation between the helicity bit and the actual beam helicity.
>> Information about the g9a Moeller runs are posted at the bottom of the
>> following page:
>>
>> http://clasweb.jlab.org/rungroups/g9/wiki/index.php/Beam_Polarization_%28Circ.%29
>>
>> I haven't followed up on that since though.
>>
>> All the best,
>> Steffen
>>
>>
>>
>> On Jan 27, 2011, at 2:54 PM, Michael Dugger wrote:
>>
>>>
>>> Hi,
>>>
>>> I would like to have a FROST approved list of target polarization
>>> directions for g9a on a run by run basis.
>>>
>>> I have been looking at the "Helicity assignment for g9a" web page at
>>> http://clasweb.jlab.org/rungroups/g9/wiki/index.php/Helicity_assignment_for_g9a
>>> and see different results!
>>>
>>> Brian has told me that I might want to use Steffen's list, but I am
>>> concerned about the comment:
>>> "The asymmetry of the 1.645 GeV data has the opposite sign without an
>>> additional sign change. This sign change needs still to be understood."
>>>
>>> We need one single FROST approved list. Does this list exist?
>>>
>>> Thanks for your time.
>>>
>>> -Michael
>>> _______________________________________________
>>> Frost mailing list
>>> Frost at jlab.org
>>> https://mailman.jlab.org/mailman/listinfo/frost
>>
>>
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