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| − | == Tricks for saving time and memory ==
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| − | * Change the binning and/or range of the built-in histograms after constructing the corresponding <span style="color:#0000FF">DAnalysisAction</span> object.
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| − | * Because there may be many <span style="color:#0000FF">DParticleCombo</span> objects for an event, perform as many cuts as possible prior to kinematic fitting.
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| − | ** This includes extremely-loose cuts (well beyond the range at which your final cut will be) on all of the physical quantities of interest (e.g. mass peaks).
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| − | * To branch an analysis, create a new (but identical) <span style="color:#0000FF">DReaction</span> object (with the same <span style="color:#0000FF">DReactionStep</span> pointers), then simply repeat or change any of the <span style="color:#0000FF">DAnalysisActions</span>.
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| − | ** If the <span style="color:#0000FF">DReactionStep</span> objects are re-used, the framework will realize that the <span style="color:#0000FF">DParticleComboBlueprintStep</span> objects will be the same, and will simply reuse them.
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| − | *** Note that the <span style="color:#0000FF">DParticleCombo</span> objects will not be identical since they will contain a pointer to a different <span style="color:#0000FF">DReaction</span>.
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| − | *** If the kinematic fit type is also the same, it will skip the kinematic fit of the new <span style="color:#0000FF">DParticleCombo</span> objects entirely and just copy the previous results since they will be identical.
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| − | == RF Beam Bunch Selection & PID Details ==
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| − | === How (Default Tag) RF bunch selection works for an event ===
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| − | * In <span style="color:#0000FF">DEventRFBunch_factory</span>: Use (in order of preference) (need at least one of):
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| − | # Tracks with good tracking FOM: SC hits
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| − | # Tracks with good tracking FOM: BCAL/TOF/FCAL hits
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| − | # All Tracks: SC hits
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| − | # All Tracks: BCAL/TOF/FCAL hits
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| − | # All Neutral Showers (assume all PIDs = photon)
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| − | # Use original DRFTime and set DEventRFBunch::dMatchedToTracksFlag to false
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| − |
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| − | * Vote: select the RF bunch that matches the most times. The RF bunch times are the DRFTime +/- multiples of 2.004 ns.
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| − |
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| − | === How (Combo Tag) RF bunch selection works for each combo ===
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| − | * In <span style="color:#0000FF">DEventRFBunch_factory_Combo</span>:
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| − |
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| − | # For each charged track in the combo, calculate its start time (from BCAL/TOF/FCAL hits)
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| − | # For each photon shower in the combo, calculate its start time (use weighted avg vertex-z of charged tracks)
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| − | # Calculate the weighted average start time from the above times.
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| − | # Select the RF bunch that is closest to this time.
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| − |
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| − | === How DChargedTrackHypothesis PID FOM calculation works ===
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| − | * Determine the track start time:
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| − | ** Try: match the track to its RF bunch using the method described above.
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| − | ** Else try: use the DEventRFBunch RF time if it was matched to other tracks.
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| − | ** Else try: use the measured track t0 time (ST, CDC) (will fail if t0 time = t1 time (e.g. both CDC (e.g. no ST/TOF/etc. hits of any kind)))
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| − | ** Note: each track may match to a different RF bunch: this allows the correct PID to be determined for background tracks originating from nearby beam buckets.
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| − | * Propagate both the TOF/BCAL/etc. time and the RF time to the track vertex, and compare them to calculate FOM.
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| − |
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| − | === How DNeutralParticleHypothesis PID FOM calculation works ===
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| − | * Propagate photon shower times to the target center, compare them to the <span style="color:#0000FF">DEventRFBunch</span> time. PID FOM is disabled for massive showers (e.g. neutrons).
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