Getting back into analysis! Status update.

This blog will serve as a "lab notebook" for my analysis of hyperon semi-leptonic decays using the GlueX experiment.

Today is the end of the Spring 2019 semester, and I'm getting back into the analysis.  Current issues are with vertices:

1. A non-trivial number of signal events have both primary and lambda vertices assigned to the same point in space (roughly 800 events out of 250k that make it through the analysis chain).  This should not be possible.  One explanation could be that the kinfit does not converge for these events (and I'm letting them into the datastream anyway???), and it freaks out and assigns all particles the same vertex location.  This is speculation.

2. The vertexing for the Lambda decay vertex seems to be too good.  There is no appreciable difference between the transverse discrepancy distribution for signal and fastpi background.

WHAT AM I DOING ABOUT IT NOW?

1. rebuilding fastpion hdgeant4.  I think that Richard has updated this over the last few months, and a new build is good.  On this point, I have a script that adds all of the necessary changes to the hdgeant4 that is gotten from git, but the script does NOT softlink the patches.  Remember to

mmcc @ HDGeant4$ ln -s G4.10.02.p02fixes G4fixes

2. Reprocess all MC.  Might want to check with Hao about the KF fix -- should I go back to using the main branch rather than his fork?

3. Reinvestigate how DSelector gets the vertices for particles... also what cuts I'm applying.  Probably want to keep them as loose as possible at this stage.

4. Look at distributions of raw and processed vertices.  Megan Perry will assist later in the summer.

K THX BAI

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Update -- probably want to pull the master HDGeant4 and modify it.  Looks like a lot has been added, and the changes have not trickled into the primarypionzapper branch.

Update -- successfully rebuilt master... testing now... Had to change run number in control.in to 31000 (or presumably something else).

../bin/.../hdgeant4 run.max works, but there is a huge spew (~10k lines) of particle def output at the top of the output.  Possibly find a way to disable this...

Now adding PPZ stuff.

Update -- wrapped decay now works, but (oddly) needed to comment out the BEAM card in control.in in order to get the particle gun card to work.  I don't remember having to do this before...

hdgeant4 now give about 10k lines of G4ParticleDefinition output when it's called.  Did some googling, but it seems that there is not an easy way to silence this.  Someone from Daya Bay has a very detailed workaround for their toolchain.  Will ask around the collaboration.

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Purging old MC and regenerating now.  300 * 10k = 3M events for each decay.