1. Pipeline Application

This chapter will give a brief example of how to run the pipeline application from command line.

1.1. Working on LXPLUS

A public build of NA64sw is available for LXPLUS users by path /cvmfs/na64.cern.ch/sft/LCG_105/x86_64-el9-gcc13-opt/ and it’s ready for public disposal. This build relies on more recent system software components, so one have to override LXPLUS’ default environment with a special command before proceed with this tutorial:

$ source /cvmfs/na64.cern.ch/sft/LCG_105/x86_64-el9-gcc13-opt/this-env.sh
$ module load na64sw/0.6.9-opt

  • LCG (provided by CERN) of certain version is used to provide common up-to-date environment for software build

  • Linux environment modules are used to provide switchable environment on top of LCG.

Once above commands evaluated in the command line, one can run the software, for instance:

$ na64sw-pipe --help

The main application provided by NA64sw is na64sw-pipe. This is a versatile entry point to data processing procedures for common needs.

1.2. Running the app

One can run immediately on some raw NA64 data chunk (we specify a number of events to read with -N/--max-events argument, otherwise processing whole chunk may take some time):

$ na64sw-pipe -N 1000 /eos/experiment/na64/data/cdr/cdr01002-003292.dat

The application will read data from provided file and perform a series of procedures on every event taken from the chunk. Result of this data processing shall appear in a current working directory in a newly created processed.root file.

During the operation a minimal set of messages is performed by default, so do not worry about quiet output.

Tip

One can view output file with ROOT by opening it with TBrowser for instance.

$ root
root> new TBrowser

Find the processed.root file on the tree-view panel and open it by double-clicking on its icon.

https://cernbox.cern.ch/index.php/s/5VbqX1w2GsXnz9X/download

Within this file, various histograms shall appear. It contains some pretty basic plots (similar to ones generated by the COOOL) or more complex plots related to reconstructed data analysis.

What precisely shall appear in this file is defined by special configuration files that we will further refer as pipeline configs. By default, na64sw-pipe uses one located at $NA64SW_PREFIX/share/na64sw/run/default.yaml. This is pretty generic one, intended to perform common lowest-level reconstruction.

There are more specialized one. For instance, $NA64SW_PREFIX/share/na64sw/run/std/apv.yaml does only basic reconstruction for APV detectors, without reconstruction on calorimeters and building any plots in the output file. You may provide pipeline config with -r/--run option, like:

$ na64sw-pipe -N 1000 --run $NA64SW_PREFIX/share/na64sw/run/std/apv.yaml \
        /eos/experiment/na64/data/cdr/cdr01002-003292.dat

Config file essentially defines what the pipeline actually does. One can have different pipeline config files for, say, calorimeters calibration and another, way more complex, for physical analysis.

1.3. Getting help

The na64sw-pipe application provides basic reference on its command line interface with -h/--help option. Using these options one can:

  • Change the type of the input data source – NA64 MC output files, use p348reco reconstruction results as an input, etc.

  • Name the output file (instead of default processed.root)

  • Provide calibration settings and logging configuration from different locations

  • Specify additional loadable runtime extensions: user’s handlers, calibration data formats, input codecs, etc

This options are not logically related to the analysis iself (run config is responsible for that), but adjusts application behaviour for certain environment (to be ran, for instance under CERN’s HTCondor batch system).