[Frost] target polarization

[Steffen Strauch]

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
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