Attendees: Ashot, Chao G, Chao P, Dipangkar, Eugene, Haiyan, Kondo, Mahbub, Maxime, Nilanga, Weizhi, Xinzhan.


Weizhi:
Cross section results extended to beyond 2 degree. Use integrated Moller event selection method.

There is a 2% difference between data and MC for the ratio of ep/Mott, which is being investigated.

<TASK> make plot with horizontal scale in log.

Consistency check for GEM efficiency, between Xinzhan and Weizhi, shows about 0.5% difference for ep, due to cut difference. Much more consistent for ee. There re a few angles that are different. That could be because of HyCal cluster size 
cut. Xinzhan uses this cut while Weizhi does not.

<TASK> compare all cuts and make sure they are consistent.

The wriggles at small angles maybe due to HyCal resolution and/or overlap between GEMs

<TASK> check by changing the log weight parameter for the resolution.

Comparing the hybrid and integrated event methods compared in region where they overlap. (Hybrid the GEM eff, cancel out while integrated method the ep and ee efficiencies are included separately). There is lot more fluctuation in the integrated values before the GEM efficiency are allowed.

<TASK> Check with just total Moller without angle cut.

Compared ep/ee from data vs MC, there is large discrepancy for the lead glass part.

Compare regions where there is only crystal (at corners) vs regions where there is some overlap with LG. This study shows that the ep yield in the sectors where there is only crystal is higher than the sectors which share between crystal and LG.

<TASK> Check the HyCal only yields without GEM information.
<TASK> check data and MC separately to find out which is wriggling.
  
Yield ration (ep to integrated ee) for the 4 sectors of LG. There is no systematic pattern, they behave the same. 

<TASK> Check for the effect of accidental GEM events in LG (should be larger) vs crystal. 

Continue to test the ee generator.

Maxime
Sees the same behavior in the (ep/integrated ee) as Weizhi.

The ep yield for different LG sectors show consistency within statistics.
also consistent with Weizhi's study.

Xinzhan:
GEM efficiency:
There are only one gas bottle change during the production so time dependence of efficiency not due to gas change.

Efficiency drops in region where clusters are centered in the transition.
Need to check dependence on the search radius for these regions.
Review how HyCal is being used for GEM efficiency.

Efficiency in overlap area of the two GEMs shows a 5% difference when relying in Hycal vs when just using the GEMs to calculate efficiency. 

<TASK> understand this difference.