1) When determining the scaling factors between data and MC, I have noticed that, even after requiring GemDeltaEventTime>10000, there were stil low energy tails
(run700001942 - 500 evts/spill !!! - 280 GeV - 30 deg) :
2) We had already seen that after requiring GemDeltaEventTime>10000 there was still a problem, but at the level of only 2-3% :
3) Let's look at the energy in layer 6
(run700001942 - 500 evts/spill !!! - 280 GeV - 30 deg) :
4) Let's look at the energy in the xtal which is along the trajectory of the electrons : layer 6, xtal 7
(run700001942 - 500 evts/spill !!! - 280 GeV - 30 deg) :
5) As already seen, there is no exact correlation between layers, between xtals, so the fraction of bad events is more than 5%. For this run, requiring that all layers energy are well measured leads to 10% of bad events. Unfortunately there is no standard cuts for that problems so far (on top of GemDeltaEventTime>10000) and one has to check run by run, layer by layer...
(run700001942 - 500 evts/spill !!! - 280 GeV - 30 deg) :
For this run : CalELayer4>7000 and CalELayer6>10000 and CalELayer5>9000
