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Some TOF Space Point Performance Plots

All plots are also included in the attached .tar file.

Space Point Creation Efficiency

Efficiency by Slab

0.5 ns
0.5 ns
1 ns
1 ns
3 ns
3 ns

Efficiency by Pixel

0.5 ns
0.5 ns
1 ns
1 ns
3 ns
3 ns

Space Point Multiplicities

Simple Multiplicity Distribution

0.5 ns
0.5 ns
1 ns
1 ns
3 ns
3 ns

Relative Multiplicity Distribution w.r.t. Single Space-point

0.5 ns
0.5 ns
1 ns
1 ns
3 ns
3ns

Space-point Spatial Distributions

0.5 ns
0.5 ns
1 ns
1 ns
3 ns
3 ns

Fake Space Point Creation

Incentive

  • How bad do we do when we extend the slab DT cut for space-point reconstruction
  • depending on slab-DT cut, how likely it is, that a fake space point is created
  • space points are created by matching slab hits based on their hit times
  • these slab hits come from multiple particles arriving around the triggered event
  • if by chance 2 particles caused hits within 3 ns, their slab hits may be wrongly matched

Method

  • count how many accidental space points can be created from slab hits in slab DT interval outside the region of interest (+-0.5,1,3 ns)
  • select the interval based on slab DT distribution (below)

  • recalculate to the cut interval width -> estimation of fake/accidental space points reconstructed
  • parameters used:
    • accidental slab DT interval: (-610,-10) ns
    • DT cuts checked: 0.5 ns, 1 ns, 3 ns

Example

  • DT cut 3 ns
  • found 200 possible slab combinations with DT in interval (-610, -10) ns
  • in total 100 space points were reconstructed
  • => expected number of fake space points = 200 * 3 / 600 = 1
  • => fraction of fakes expected in reconstructed space points = 1/100 = 0.01

Results

10248
DT cut TOF0 TOF1 TOF2
0.5 ns 3e-4 3e-5 5.5e-5
1 ns 6e-4 7e-5 1e-4
3 ns 2e-3 2e-4 3e-4

Tab. Fractions of expected fake/accidental space points for run 10248.

Distributions of fraction of fake space points event by evet:
Distribution of expected fake space point number over reconstructed number of space point for each event. Run 10248 with slab DT cut at 0.5 ns
Run 10248 with DT cut set to 1 ns.
Run 10248 with DT cut set to 3 ns.

Conclusion

  • taking into account all triggered events, most of the fake space point reconstructions happen in TOF0
  • this is expected as TOF0 sees the largest particle flux
  • when increasing DT cut from 0.5 ns to 3 ns, fraction of fake SP increases by a factor of ~6
  • due to the bunched nature of the slab DT, estimation based on count of fake SP in DT interval (-610,-10) ns underestimates the actual contribution in the signal region, (+-3 ns). The underestimation is likely by a factor 2 or more
  • most of the fake/accidental space point will be result of multiple particles hitting the TOF
  • in the physics analyses, we are interested in single particle triggers => mis-reconstruction of such events is unlikely

Updated by Pec, Viktor over 2 years ago · 24 revisions