Hi.
in !44011 (merged) we switched on the MdtCalibrationDbTool by default as we thought that the calibration constants should be taken consistently from the database in both reconstruction and digitization. However, this caused a severe drop in the muon reconstruction performance in simulation from 22.0.37 onwards (c.f the screenshot below) and was first reported by the trigger group in ATR-23768 and then mainly discussed in ATLASRECTS-6449. Actually, this development is not the cause of the feature observed in the ticket ATLASRECTS-6449 but definitely a blocker for its solution. We found that in earlier times the t0 in digitization and reconstruction was put to 800 and 817 ns by intention and that this shift actually matters in the reconstruction chain downstream, also (cf. the same screenshot attached below). We do not know what the 17 ns emulate exactly but for the sake of restoring the muon reconstruction performance in simulation, a property is added to the MdtDigitizationTool to shift back the t0 values towards the 800 ns.
Tests have been performed thus far on 10k dimuon events with pt ranging between 2 and 15 GeV and within abseta<1.05
Tagging @mvanadia, @gartoni, @bernius, @jchapman, @okumura for information.
Also tagging: @sroe, @npetters, @goblirsc, @pgadow for another episode of the philosopher of the day
