...
- Basic version of the code: tagghosts.C
- Another version of the code, algorithm is the Johan's one, but output is a tree with number of tagged xtals and sum-of-energy of tagged xtals for the first 3 cluster tagghosts_v1.C .
Overlay energy for tagged
...
clusters
I run the tagghosts_v1.C on the 100 AG-GR-v19r4p1gr14-OVL, and looked at the Overlay energy in the first and second cluster vs. the ghost-tagged energy.
The selection is just trigger and filter and CalNumClusters>0. I also required that there is at least 1 tagged xtals, if there are no such xtlas there is nothing to say.
Few details on the algorithm:
- There are two tagging options: conservative (if both xtal ends are ghost-like) and permissive (if at least one xtal end is ghost-like).
- I used 'permissive' since purity is high and efficiency is low (see below).
- The energy threshold for tagging a xtal end is set to 120 MeV (no good reason for this number, need to be optimized).
Here the plots for first (left) and second (right) cluster.
The next step is check if we can lower the energy threshold down to the nominal 100 MeV to increase the efficiency.
If the energy is too low we can tag good xtals as ghost.
I made few reprocessing of the AG-GR-v19r4p1gr14-OVL with threshold at 120, 110, 105, 100 MeV, and plotted the Overlay energy fraction in the first cluster vs. the fraction of ghost-tagged energy.
Same selection as before, including the request of at least one tagged xtals.
The plots below show the permissive case (left) and the conservative case (right) for the 4 energy thresholds.
The higher the number of events in the plot, the higher the efficiency we can expect.
Note that the conservative case is always worse than the permissive case.
In the highest efficiency case (permissive, 100 MeV), there are few events with overlay energy = 0.
My personal best choice, among these, is permissive 105 MeV. That's why I put another plot here:
My first conclusions are:
- Johan algorithm works fine!
- Clusters with at least one ghost-tagged xtal tend to have large overlay energy.
- It never happen that Only in one case the overlay energy is 0 and there is some ghost-tagged xtal (thanks also mostly connected to the energy threshold set to 120 MeV). 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/CalawEnergySum)> 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)
...