MCPL - Monte Carlo Particle Lists

MCPL files, with extensions .mcpl and .mcpl.gz is a binary format for usage in physics particle simulations. It contains lists of particle state information, and can be used to interchange or reuse particles between various Monte Carlo simulation applications. The format itself is formally described in:

T. Kittelmann, et al., Monte Carlo Particle Lists: MCPL, Computer Physics Communications 218, 17-42 (2017), https://doi.org/10.1016/j.cpc.2017.04.012

All MCPL code is provided under the highly liberal open source Apache 2.0 license (http://www.apache.org/licenses/LICENSE-2.0), and further instructions and documentation can be found at https://mctools.github.io/mcpl/.

The mcpl-python package

The mcpl-python package provides a Python API for working with MCPL files. More details about the Python API and how to use it can be found at the https://mctools.github.io/mcpl/usage_python page.

Additionally, the package also provides the command-line tool pymcpltool, which has similar capabilities as the binary mcpltool from the mcpl-core package. The main difference being an ability to extract statistics and plots from MCPL files, and that the pymcpltool (unlike the mcpltool) only provides read-only capabilities.

Note that it is recommmended for most users to simply install the package named mcpl, rather than referring to the package named mcpl-python directly.

Scientific reference

Copyright 2015-2026 MCPL developers.

This software was mainly developed at the European Spallation Source ERIC (ESS) and the Technical University of Denmark (DTU). This work was supported in part by the European Union's Horizon 2020 research and innovation programme under grant agreement No 676548 (the BrightnESS project).

All MCPL files are distributed under the Apache 2.0 license, available at http://www.apache.org/licenses/LICENSE-2.0, as well as in the LICENSE file found in the source distribution.

A substantial effort went into developing MCPL. If you use it for your work, we would appreciate it if you would use the following reference in your work:

T. Kittelmann, et al., Monte Carlo Particle Lists: MCPL, Computer Physics Communications 218, 17-42 (2017), https://doi.org/10.1016/j.cpc.2017.04.012

Support for specific third party applications

Note that some users might also wish to additionally install the mcpl-extra package, which contains cmdline tools for converting between the binary data files native to some third-party Monte Carlo applications (currently PHITS and MCNP[X/5/6]). Users of Geant4 might wish to install the mcpl-geant4 package, which provides C++ classes (and CMake configuration code) for integrating MCPL I/O into Geant4 simulations. Finally, many Monte Carlo applications have directly integrated support for MCPL I/O into their codes. At the time of writing, the list of applications with known support from MCPL I/O includes:

• McStas (built in)
• McXtrace (built in)
• OpenMC (built in)
• Cinema/Prompt (built in)
• VITESS (built in)
• RESTRAX/SIMRES (built in)
• McVine (built in)
• MCNPX, MCNP5, MCNP6 (based on ssw2mcpl/mcpl2ssw from the mcpl-extra package)
• PHITS (based on phits2mcpl/mcpl2phits from the mcpl-extra package)
• Geant4 (based on C++/CMake code from the mcpl-geant4 package)

Note that instructions for installation and setup of third-party products like those listed above are beyond the scope of the MCPL project. Please refer to the products own instructions for more information.