Gleam User Guide: Output
Gleam User Guide: Output
All Gleam output is in ROOT format. To read and analyze these files you will need to use an application capable of reading ROOT files. The easiest path is to use the ROOT analysis environment. For more general information about ROOT and how we use it in GLAST, please see the GLAST ROOT home page.
Those of you familiar with the GLAST AO, will recall that
the simulation output an ASCII ntuple. This
file has now been replaced by a ROOT ntuple.
The data is tabular, where for each event, there is a fixed-length row of data. Each column corresponds to a particular ntuple element. The set of ntuple entries is defined in the following web page:
http://www-glast.slac.stanford.edu/software/gleam/MinimalTuple.htm
To read this ntuple, you need to use ROOT. The currently supported version of ROOT is distributed with GlastRelease..
If you desire to make your own customized ntuple, then you should utilize the ntupleWriterSvc.
More complex data is also available as output. This data is stored in ROOT Trees. All data produced in the simulation or reconstruction is stored in ROOT Trees. The summary ntuple is constructed from the data contained in the full ROOT Trees. ROOT trees provide a mechanism to store objects. We currently support 3 types of ROOT trees: Monte Carlo, Digitization, and Reconstruction. Each contains the event and run numbers to allow unique identification of each event. The sections that follow describe each of the ROOT trees.
The Monte Carlo record is stored in a ROOT file using the MC ROOT classes. A full description of the Monte Carlo ROOT classes is available here.
The resulting digitization data from all detectors is stored in the digi ROOT classes. A full description is available here.
Another ROOT file may be created that contains more detailed reconstruction data. It contains tracks as determined by TkrRecon, energy reconstruction for each CAL log, and the summary data for the ACD such as DOCA. A more complete description of the GLAST Recon ROOT file is available here.
H. Kelly Last Modified: 2004-07-23 09:13:42 -0700