[Halld-physics] 2pi, 2Kaon,1proton

[Beni Zihlmann]

Hi Nathan and all,
attached is a root file with some histograms looking at the events
discussed in the last physics meeting. 2 negative pions, 2 positive
kaons and 1 proton in the final state.
I generated 5000 events thanks to Nathan for the file.
The histograms are generated by my diagnostic code that takes
advantage of the additional stored truth information in hdgeant.
It may help understand why this particular event topology is
very difficult to analyze.
In the following is a short explanation of the spectra:

hist[0] shows number of all generated particles in each events
hist[1] shows number of generated charged particles for each event
hist[2] shows the number of track candidates for each event
hist[3] shows the number of hits per track candidate for all events

hist[31] momentum distribution of first particle (high momentum kaon)
hist[32] momentum distribution of proton
hist[33] momentum distribution of first pion
hist[34] momentum distribution of second pion
hist[35] momentum distribution of second kaon (low momentum)
-> From this you can see that the topology of these events is that there is
      ALWAYS a very high momentum kaon in the forward direction and two
      very low energy pions.


hist[5] shows the number of hits per track candidate where the majority of
            hits come from the first thrown track namely the high 
momentum kaon
hist[6] same for second track (proton)
hist[7] same for third track (first low momentum pion)
hist[8] same for fourth track (second low momentum pion)
hist[9] same for fifth track (second low momentum kaon)
hist[4] same where the majority of hits originate from a particle other 
then the
            thrown once.

hist[10] shows the ratio of reconstructed momentum divided by the generated
              momentum for the first particle (high momentum kaon)
hist[11] same for proton
hist[12] same for first pion
hist[13] same for second pion
hist[14] same for low momentum kaon

ignore histos 15 to 20 because they are related to PID which is not 
really meaningful
since we do not have PID on kaons yet.

hist[21] to hist[25] show how much of the hits of a track candidate 
belong to the true
                               thrown track. Note there is an entry for 
each track candidate.

hist[26] number of track candidates where the majority of hits are 
caused by the thrown
              track number 1 (high momentum kaon)
hist[27] same for track 2 the proton
hist[28] same for first low momentum pion
hist[29] same for second low momentum pion
hist[30] same for second low momentum kaon.

that's all,
Beni














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