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6 changes: 3 additions & 3 deletions docs/advanced-specifics/trackToCollAssoc.md
Original file line number Diff line number Diff line change
Expand Up @@ -52,18 +52,18 @@ Let's define $$BC_{track}$$ the BC of the middle of the readout window of the tr

In the AO2D files, $$BC_{track}$$ = `track.collision().bc() + track.trackTime() / o2::constants::lhc::LHCBunchSpacingNS;`

The cut applied on the BC difference $$\lvert BC_{track}-$BC_{coll} \rvert$$
The cut applied on the BC difference $$\lvert BC_{track}-BC_{coll} \rvert$$
is the following:

$$\lvert BC_{track}-$BC_{coll} \rvert$$ < `bcWindowForOneSigma * nSigmaForTimeCompat + timeMargin / o2::constants::lhc::LHCBunchSpacingNS;`
$$\lvert BC_{track}-BC_{coll} \rvert$$ < `bcWindowForOneSigma * nSigmaForTimeCompat + timeMargin / o2::constants::lhc::LHCBunchSpacingNS;`

With `bcWindowForOneSigma`, `nSigmaForTimeCompat` and `timeMargin` being configurable variables.

These variables must be cautiously configured to avoid eliminating possible time-compatible collisions with the track, and to avoid looping on numerous collisions that are very far from the track in time.

If $$coll$$ passes this cut, then a stricter cut on the time difference between the collision and the track is applied, as will be described below.

The cut is different for tracks which come from detectors with readout windows and for detectors that detect track with a gaussian-like time precision.
The cut is different for tracks which come from detectors with readout windows and for detectors that detect tracks with a gaussian-like time precision.

For detectors that collect tracks in readout windows such as the ITS and the MFT, $$t_{track}$$ is the middle of the track readout window in $$ns$$. Its associated time uncertainty is $$\sigma_{track}=\frac{\text{readout window duration}}{2}$$. $$t_{track}$$ is then associated to a box-like time error, and meaning that the track crossed the detector in the time range $$[t_{track}-\sigma_{track}, t_{track}+\sigma_{track}]$$

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