Kinematic fitting charged particles 11/16/11
Looking at an all charged particle final state to study the state of the tracking code: \gamma p -> pi+ pi+ pi- pi- p.
- 50,000 events
- svn revision 8540
All combinations of track hypotheses that produce the correct final state are kinematically fit. Constraint is overall conservation of 4-momentum.
- 41% of events have sufficient particles (>=3 positive tracks, >=2 negative tracks)
- Of these, 9% have kinematic fit confidence level>1% (4% of total events)
Kinematic fit is dependent on errors, PID. Try to simplify things...
Look at events with exactly 5 tracks (3 positive, 2 negative) and look at sum of reconstructed 3-momentum from all tracks.
28% of events have exactly 5 tracks
2400 events in region outlined in red.
- svn rev. 8574
Distribution of thrown protons in events:
Look at sample of proton-only events with same momentum distribution.
Protons with p<300 MeV/c are not detected, those with p>450 MeV/c almost always have sufficient hits.
Full event (5 particle final state) sample:
- Examine only events with proton p>450 MeV (57% of total events)
- 66% of events have good proton hit selection (all hits associated with proton hypothesis from proton track)
- Of these events, only 54% have good fit (confidence level from tracking chi^2 > 1%)