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So far original Selection 1 looks optimal.

Searching for peaks in "Whiskers" region

Parameters

Set in psana.cfg file peak selection parameters pretty much the same as in Arc region

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Combined distributions for two regions

Difference between averaged azimuth angles in two regions

Orientation angle

Image Added

Remarks

1. Peak radius equal to 3 or 5 pixel with low and high thresholds 10 and 150ADU, respectively, work fine.

2. More than 90% events have more than 2 peaks in each side of "whiskers" region. Constrains on number of peaks >1 in each region should be used to select good single-hit events.
3. Constrain on phi_std<0.5 or phi_ptp<1 can be used to select good single-hit events.
4. Average azimuth angle can be used as a measure of event orientation.

References

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