FSRoot is an alternative to DSelectors that uses flat trees.
There are two steps:
1. Use FlattenForFSRoot (hd_utilities/FlattenForFSRoot) to generate flat trees from the standard analysis trees.
> flatten -in [input file with analysis tree] -out [output file with flat tree]
- Run flatten with no flags to see further run options.
- This should work for data, reconstructed MC, and thrown MC.
- See FlattenForFSRoot/Documentation/GlueXFSRootFormat.pdf for more information.
2. Use FSRoot (available at https://github.com/remitche66/FSRoot) to make histograms from the flat trees.
- See FSRoot/Documentation/FSRoot.pdf for documentation.
Here is a working example:
1. Flatten an analysis tree:
> flatten -in /u/home/remitche/FSRootExample/analysis.root -out flat.root
- where analysis.root was created by running /u/home/remitche/FSRootExample/MC.run
- which generates MC based on the config file /u/home/remitche/FSRootExample/MC.config
- which simulates the process gamma p --> eta' p --> eta pi+ pi- p --> (pi+ pi- pi0) pi+ pi- p using genr8 with the input file /u/home/remitche/FSRootExample/MC.genr8
2a. Make a plot of the eta' mass using a cut on the chi^2/dof:
- where particles 2-6 are the five pions from the eta' decay
2b. Skim the tree to a new file using a cut on the chi^2/dof: