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Note, though, that it can have a larger effect on the calculated longitudinal position if only one end of the xtal has FHE firing. This can happen near one end of a xtal, where because of the light taper, the optical signal at the near end is larger than at the far end. See the plot below, which is the average over all crystals, where Sasha finds evidence for a bias of up to a few mm in the segments near the ends of the average xtal near the 1 GeV FHE threshold. Note that the bias is in the direction we expect: it is positive for segment 10, where the signal is typically ~30% bigger than the signal at the negative end (and vice versa in segment 1).
In these plots, Sasha has converted the measured asymmetry to longitudinal offset using the average xtal asymmetry slope (as usual). The segments (slices, whatever) are labeled 0 to 11, where 0 is closest to the negative face and 11 is closest to the positive face.
Tests to perform on an AGN skim or hard pulsar skim
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