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This effect deteriorates the reconstruction of the direction of the event in the calorimeter; which is clearly observed in the distributions of the variables Trk1ZDir and CalZDir shown in MuonPisaReconstruction.gif, MuonPisaReconstruction.ps and MuonPisaReconstruction.root(gif, ps and root files). Note that (for this data and selection applied) the muon direction in the calorimeter (CalZDir) is properly reconstructed for ONLY a TINY FRACTION (about 3%) of the events.
Additional muon runs
From From the list of muon runs in the Beam test data base, only 2 runs are shown as " Vertical Runs". I took run number 700000322, which has 10^5 events (5962 seconds of data, taken on 2006/07/15). Before inspecting the data with FRED i applied the same selection criteria used above (vertical events within 5 deg which deposit some energy in teh cal) and ONLY 2 events survived. Later on i noticed that indeed, most events are empty (CalEnergyRaw < 10 MeV).
Anyway, the FRED display for the two events which survived can be foundat Evt0 and Evt1. Note that behaviour is similar to the one described above.
Electrons @ 5 GeV
David please include run numbers
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