Geant4 Python Application

This is an experiment at providing a pythonic interface to Geant4.

The goal is not to provide a full python interface to Geant4, but rather to provide a high-level interface to a generic Geant4 application which is highly configurable.

If you are looking for a full set of python bindings for Geant4, I recommend looking at geant4_pybind.

Overview

• Configurable Geant4 application written in C++
• Python interface to the application via pybind11
• The complete event data is available as an awkward array for further analysis

Installation

A lot of work has been done to make the installation as easy as possible. This package is fully pip installable and should work on all major platforms.

The package itself does not contain any Geant4 data files. These files are needed to perform any kind of simulation. They will be downloaded to a temporary directory automatically during simulation startup.

pip install geant4-python-application

Geant4 data files

The Python wheels for this package do not contain any Geant4 data files due to their size. These files will be downloaded on demand without the need of any user interaction.

The default location for these files can be obtained by calling:

python -c "import geant4_python_application; print(geant4_python_application.get_data_path())"

Uninstalling the package will not remove the data files. The user is responsible for removing them manually.

Overriding the default data path

The default data path can be overridden by calling application_directory. This should be done before the application is initialized.

from geant4_python_application import application_directory

application_directory("/some/other/path")

Overriding the default data directory is encouraged when submitting batch jobs to a cluster in order to avoid downloading the data files multiple times. In this case the application directory should point to some shared location.

Using a temporary directory

A temporary directory can be used by calling:

from geant4_python_application import application_directory

application_directory(temp=True)

The operating system will take care of cleaning up the temporary directory.

It is possible that the operating system will delete only some of the files in the temporary directory which can lead to a Geant4 runtime error. In this case it's recommended to delete the temporary directory manually and let the application recreate it again.

Usage

import geant4_python_application as g4

# Use a temporary directory for the Geant4 data files (remove this line to use the default location)
g4.application_directory(temp=True)

with g4.Application(gdml=g4.basic_gdml, seed=137) as app:
    events = app.run(n_events=100)

print(events)