[Rgc_analysis] [EXTERNAL] 8.7.0 TBT Target Polarization

[Gregory Matousek]

Hi all,

I realized just now that there is no meeting planned for today. I wanted to share my findings for the inclusive DIS Tpol calculated from the 8.7.0_TBT NH3 cooks.  Please see the attached image. One can see the progression of the extracted Tpol when changing the HWP status, and when changing the NMR polarization.

Before I make comments about the plot, I wanted to address how I determine the  "direction" of anti-parallel vs. parallel from the recent cooks. What I mean by this is suppose we have a single DIS event in the hipo file with helicity = +1. We need some mechanism to determine if this event should be treated as "anti-parallel" to the target spin or "parallel" to the target spin. It would seem that the HWP status, NMR tpol direction, and solenoid magnet would play a role in this. However, as far as I know, the HWP status is already considered at the level of cooking, so we do not need to use it at the analysis stage. Since the solenoid magnet direction is constant along the analyzed run period, I only select distinguish anti-parallel vs. parallel directions depending on the NMR polarization sign.

With that being said, the Pt progression plot I included seems to show some consistent behavior, but I still have some questions. The run range I analyzed is chopped into 4 HWP sections (in, out, in, out). From the first in->out, the FCup correction boosts, then decrease the Tpol, which is what we would reasonably expect. Also, when we flip the NMR sign (closed->open markers) , the FCup correction goes from decreasing to boosting the Tpol. My concern is that when the HWP status is switched again, (out->in) the overall effect of the FCup corrections still boost the Tpol, opposite to what we saw in the first in->out transition.

I apologize for the drawn out explanation, but I think we can agree that the FCup correction mostly consistent with what we would expect with changing HWP and changing Pt. Perhaps someone could brainstorm why the out->in transition doesn't seem to flip the impact of the FCup correction in comparison to the first in->out transition.

Let me know if you have any questions,
Gregory
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