event reconstruction - E1039-Collaboration/e1039-wiki GitHub Wiki
This page overviews the variables of tracks and dimuons that are reconstructed by kTracker. The variables are stored in SRecEvent. The exact definition of the variables should be found in the source code.
Variable | Meaning |
---|---|
charge | +1 for μ+ and -1 for μ-. |
num_hits | The number of drift-chamber hits associated with this track. |
chisq | χ2 of track fitting with drift-chamber hits. |
chisq_target | |
chisq_dump | |
chsiq_upstream | |
Variable | Meaning |
---|---|
pos | The initial position of dimuon |
mom | The initial momentum of dimuon |
mom_pos | The initial momentum of μ+ |
mom_neg | The initial momentum of μ- |
Tracklet
is an intermediate object made during the track reconstruction in kTracker.
Type | Station ID | List index | Note |
---|---|---|---|
D0 tracklet | 1 | 0 | |
D1 tracklet | 2 | 0 | |
D2 tracklet | 3 | 1 | |
D3p tracklet | 4 | 2 | |
D3m tracklet | 5 | 2 | |
D2+3 tracklet | 6 | 3 | a.k.a. back-partial track |
Global track | 7 | 4 |
The algorithm (i.e. code) can be found here. It is usually applied after the in-time cut. After the in-time cut, we suppose that all remaining hodoscope hits are in time (i.e. coming from the triggered RF bucket) but chamber hits are a mixture of in time and out of time. The c-to-h matching is to remove the remaining out-of-time chamber hits.
In the c-to-h matching, we check if each chamber hit matches with any hodoscope hit in X-Y plane at the station of the chamber hit. If so, the chamber and hodoscope hits should be created by an in-time muon, and thus the chamber hit is kept. If not, the chamber hit is removed.
- Overall reconstruction flow: DocDB 1283
- Updates: DocDB 1683
- Sec. 4.2 of Kei's PhD thesis
- kTracker Q&A @ E906 UIUC TWiki