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Hi Brad, So just applying this cut to the real data is sufficient to make mc and data look very similar regarding the hole at Eb/2? Is there anything unique about the quality of these Moller tracks/clusters in the real data with E1>Eb/2 && E2>Eb/2 compared to the others? Is there evidence of more background in your Moller selection for these events? e.g. in a plot of E1 vs E2, M vs E1-E2 and E1+E2, or just M or E for (E1>Eb/2 && E2>Eb/2) and (E1<Eb/2 || E2<Eb/2)? -Nathan On May 19, 2016, at 23:29, Bradley T Yale <[log in to unmask]> wrote: > I think the mystery of the Moller gap has finally been solved. > > Looking at the reconstructed Moller events generated with the fixed cross section, not much was changed, > so I explicitly forced the condition such that if one Moller had track E > Ebeam/2, then the other had to have E < Ebeam/2, and vice versa. > > Applying this to both MC and Data, along with modest ESum and phi cuts, gives the attached momentum plots. > The other distributions match much better too, particularly track position at the ECal, which now shows the gap in data as well. The higher-energy bias for hits in the bottom half of the ECal can be seen from the asymmetry in where the electrons hit. Loosening the MC cuts a little (only cutting ESum) starts to close the gap and make it look even more like the data plots. > > So in summary, the gap is likely due to electrons always being cleanly paired on opposite halves of Ebeam/2 in MC, but not necessarily in data. The gap is also apparent in background MC without forcing this condition, suggesting that the MC is too "clean". > -Brad > > > Use REPLY-ALL to reply to list > To unsubscribe from the HPS-SOFTWARE list, click the following link: > https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1 > <MC_TRACK_Energy.png><MC_tracksAtEcal.png><DATA_TRACK_Energy.png><DATA_tracksAtEcal.png><LOOSERMC_TRACK_Energy.png><LOOSERMC_tracksAtEcal.png> ######################################################################## Use REPLY-ALL to reply to list To unsubscribe from the HPS-SOFTWARE list, click the following link: https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1