[Halld-physics] GlueX Note: Orientations of the Photon Beam Polarization

[Alexander Austregesilo]

Dear Colleagues,

I extended the analysis to the recently completed Spring 2018 data set:

https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=3977

During this analysis, I noticed a mismatch between the data and the 
orientation in RCDB in 5 instances:

* run 41546 has the polarization plane oriented at 90 degrees, not 135

* run 41206 is 0, not 90

* runs 41250, 41607 and 42386 are polarized 45 degree runs, not amorphous


In addition, I changed the sign of the offset from the nominal 
orientations to facilitate the interpretation. The definition is now 
consistent with the analysis of pi0/eta/eta' asymmetries.

Thanks to Peter Pauli, Will McGinley and Richard Jones for their useful 
comments and discussions.

Best regards,

Alex



On 4/19/19 5:27 PM, Alexander Austregesilo wrote:
> Dear Colleagues,
>
> I submitted a draft of my note 'Orientations of the Photon Beam 
> Polarization for Spring 2017 from rho(770) Decay Asymmetries' to DocDB:
>
> https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=3977
>
> Abstract:
> We use the production of the rho(770) meson to extract the deviation 
> of the nominal polarization plane of the photon beam, providing an 
> estimate of the statistical and systematic uncertainties. The results 
> should be used consistently by all studies, especially for final 
> states with a limited data set which does not permit to extract these 
> offsets.
>
> In addition to the results, it includes a short introduction of the 
> method, that shows that the extracted offset psi_0 is exactly 
> equivalent to the offset phi_0 that appears in pseudoscalar beam 
> asymmetries.
>
> Please let me know if you have any corrections and suggestions.
>
> Have a nice weekend,
>
> Alex
>
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