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- Johan algorithm works fine!
- Clusters with at least one ghost-tagged xtal tend to have large overlay energy.
- Only in one case the overlay energy is 0 and there is some ghost-tagged xtal (mostly connected to the energy threshold). The 'purity' of such selection is ~1.
- Efficiency is low. We can't tag a good fraction of ghost clusters in this way.
- There are few events with low overlay energy and low ghost-tagged energy. After looking at event displays I think we can consider good cluster is the ghost-tagged energy is <~3%
- My suggestion for ghost tagging ghost clusters is "TagGhostNumXtals>0 && (TagGhostRawEnergySum/CalawEnergySumCalRawEnergySum)> 0.03"
- This is valid for permissive E >= 105 MeV.
- We can include this algorithm just after clustering, and then tag ghost clusters. Not sure how we should use this info:
- Select best cluster only if non ghost-tagged - what happen if the best cluster is also a ghost (i.e. there are no other options?)?
- Use this info in tracking ( e.g. knowing that the direction is likely to be wrong). Need Tracy here...
- Use in event-level analysis to select events with useless cal information (and treat them as tracker only if possible)
Efficiency with Periodic Triggers
I used the periodic triggers in the Calibration datasets (provided by Johan) to test the efficiency of a pure sample of ghosts.
The dataset used is Periodic_CalGhost, reprocessed with v19r4p1gr07 (not the latest, but the most recent in the DataCatalog). It has a cut on Cal deposited energy > 5 MeV.
I used only the first 20 files... I'll try to update it later.
The efficiency plot is easy: number of events selected by "TagGhostNumXtals>0 && (TagGhostRawEnergySum/CalRawEnergySum)> 0.03" divided by the total number of events.
The the plots for the permissive case (left) and conservative case (right):
The max efficiency is ~84% is reached after RawEnergy ~ 3 GeV.
I checked the effect of the request of some fraction of ghost-tagged energy (if looked necessary from AG hand scan).
The scan from 0 to 3% is in the plot below:
The effect is on the high energy side (>10 GeV) and reduces the efficiency of few percents.
Ghost number and cluster classification
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