[Rgc_analysis] [EXTERNAL] 8.7.0 TBT Target Polarization

Wed May 3 09:44:20 EDT 2023

Hi Silvia,

I admit I am not completely clear on which runs have been cooked “so far” and which ones can be trusted to be analyzed. I found Noemie’s most recent results at
https://clasweb.jlab.org/wiki/images/b/b3/PbPt_elastic_RGC_Apr25.pdf
- are there any others? In that analysis, she lists runs from two out of the 5 periods that Gregory analyzed. Maybe I’m missing the others, or Gregory used runs that haven’t been yet cooked with the newest software? In any case, I was hoping that Noemie (or someone else) could (re)analyze the runs - grouped in periods of same HWP and NMR status - that DO exist and that are reliable to use, with my suggested “weighted average” method (I believe she and Gregory agreed on this method), and perhaps even with the more sophisticated dilution factor calculation (again, Greg is using this already). Obviously just a “wish” from my side - you know best how to prioritize various possible tasks.

From the numbers in Noemie’s link above, it appears as if “Gregory's 1st period” and “Gregory’s 3rd period” have elastic PbPt of 63% and 65%, respectively (consistent within uncertainties). Gregory’s analysis seems to indicate that the 3rd period actually had a somewhat lower polarization on average, although the evidence is not very strong. The absolute values seem to agree relatively nicely given that Noemie’s values still have Pb in them (about 0.82?). So if we would divide Noemie’s results by 0.82 and plot them on top of Gregory’s, we probably would see agreement within statistical uncertainties.

Meanwhile, my request was mostly about the last 2 periods in Gregory’s analysis. He observed that the FC correction did not change sign in spite of two flips of the HWP. By comparing with elastic Pt in those 2 periods, I was hoping we could check (at least) that red data points (open circles) have a consistent trend with the elastic results. Maybe these Pt’s already exist - I just couldn’t find them easily.

Again, I apologize if I missed or misunderstood something. I am just hoping someone can plot elastic data points on top of Gergory’s DIS ones.

Thanks - Sebastian

On May 3, 2023, at 3:20 AM, Silvia Niccolai <silvia at jlab.org<mailto:silvia at jlab.org>> wrote:

Sebastian,
Noémie has been doing elastic PbPt analysis for every set of runs we have cooked so far. She presented them one week ago for the latest cooked runs. She can directly compare her results to Gregory’s. Not sure what else you’re asking for.
Best regards,
Silvia

Sent from my iPhone

On 2 May 2023, at 15:20, Sebastian Kuhn via Rgc_analysis <rgc_analysis at jlab.org<mailto:rgc_analysis at jlab.org>> wrote:

 Hi Gregory,

this looks really interesting. I think it would be GREAT if someone could extract the ELASTIC estimate for PbPt for each of the 5 groups of runs that you analyzed, to see if it follows the same trend. (In principle, one could even use the same distinction between FC-corrected and uncorrected results - although that should play a lesser role for elastic asymmetries that are bigger).

One way to address your question would be to simply look directly at the FC asymmetry for each of the 5 run periods. In principle, you are correct to expect that the FC asymmetry should be unchanged if one DOESN’T account for the sign change of NMR*HWP, and hence it should flip sign if you analyze it WITH those factors included (i.e, every time either the NMR or the HWP flip sign). However, it is quite possible that the FC asymmetry changes over time, and perhaps even right when we changed the HWP  (later in the run, we DELIBERATELY reset it everytime we changed the HWP, and Hall A may have done that already during the time you are analyzing). You could use your own code to calculate the FC asymmetry, or look at archived MYA plots.

- Sebastian

On May 2, 2023, at 8:51 AM, Gregory Matousek via Rgc_analysis <rgc_analysis at jlab.org<mailto:rgc_analysis at jlab.org>> wrote:

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" ofanti-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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