|
|
| (24 intermediate revisions by the same user not shown) |
| Line 1: |
Line 1: |
| − | == Tricks for saving time and memory ==
| |
| − | * Change the binning and/or range of the built-in histograms after constructing the corresponding <span style="color:#0000FF">DAnalysisAction</span> object.
| |
| − | * 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.
| |
| − | ** 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).
| |
| − | * 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>.
| |
| − | ** 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.
| |
| − | *** 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>.
| |
| − | *** 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.
| |
| | | | |
| − | == RF Beam Bunch Selection & PID Details ==
| |
| − | * Note: These routines assume high-luminosity running (i.e. too many tagger photons to distinguish the RF bunch).
| |
| − |
| |
| − | === How RF bunch selection works for an event (creating a single DEventRFBunch object) ===
| |
| − | * The measured RF time and variance are assumed to be zero (until actual measured values are introduced).
| |
| − | * In <span style="color:#0000FF">DEventRFBunch_factory</span>: loop over <span style="color:#0000FF">DTrackTimeBased</span> objects, determine the matching TOF/BCAL/ST hits, propagate the matching time to the target center and select the closest-matching RF bunch (+/- multiples of the RF bunch frequency).
| |
| − | ** Note: Hit-use order: use TOF hit if present, else use BCAL hit if present and track momentum > 250 MeV/c. Only use ST hit if present and no tracks have good TOF/BCAL hits to use.
| |
| − | *** TOF-hit resolution (80ps) is good enough to pick RF bunch regardless of momentum or if correct PID is used to propagate the time (e.g. won't reconstruct protons below 300 MeV/c anyway, etc.)
| |
| − | *** BCAL resolution is ~310ps at 250 MeV/c, pi/K delta-t error is ~40ps (proton too slow): 3sigma + delta-t error = ~970ps < 1.002 ns
| |
| − | *** ST resolution projected 350ps - 400ps: not good enough to select RF bunch (OK if enough voting tracks)
| |
| − | ** Note: tracks with bad vertex-z are ignored, and tracks with low track-reconstruction FOM are ignored unless there's no good tracks.
| |
| − | ** Note: if there are no TOF/BCAL/ST hits with good tracks, then tracks with low tracking FOM are used.
| |
| − | *** If still no good hits, then the track times from time-based tracking is used (first from good-tracking-FOM tracks, then all).
| |
| − | * Vote: select the RF bunch that matches the most tracks (tie broken by highest average tracking FOM).
| |
| − |
| |
| − | === How DChargedTrackHypothesis PID FOM calculation works ===
| |
| − | * Determine the track start time:
| |
| − | ** Try: match the track to its RF bunch using the method described above.
| |
| − | ** Else try: use the DEventRFBunch RF time if it was matched to other tracks.
| |
| − | ** 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)))
| |
| − | ** 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.
| |
| − | * Propagate both the TOF/BCAL/etc. time and the RF time to the track vertex, and compare them to calculate FOM.
| |
| − |
| |
| − | === How DNeutralParticleHypothesis PID FOM calculation works ===
| |
| − | * Propagate shower times to the target center, compare them to the <span style="color:#0000FF">DEventRFBunch</span> time.
| |
