Kinematic fitting charged particles 11/16/11

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Looking at an all charged particle final state to study the state of the tracking code: \gamma p -> pi+ pi+ pi- pi- p.

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.

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 should mostly be reconstructable.