LArSoft  v08_42_01
Liquid Argon Software toolkit -
MPI/Examples : exMPI02


An example of dosimetry in a water phantom.


  • Geometry : water phantom
  • Primary : broad beam (200 MeV proton)
  • Physics List : FTFP_BERT
  • Analysis : ROOT histogramming

The environment variables, G4LEDATA, G4LEVELGAMMADATA and G4SAIDXSDATA are required for data files.

The enviromnet variable, ROOTSYS, is set to the root path of the ROOT package.


  • Score dose distribution in a water phantom.
  • Learn how to paralleized your applications.
  • Create a ROOT file containing histograms/trees in each node. Each slave node generate a ROOT file, whose file name is different from each other.

How to build

Use CMake on Geant4 library installed with CMake build.

This example requires G4mpi library to be installed (see examples/extended/parallel/MPI/source/

Follow these commands,

> mkdir build
> cd build
> cmake -DG4mpi_DIR=<where-G4mpi-wasintalled>/lib[64]/G4mpi -DCMAKE_CXX_COMPILER=mpicxx \
  -DGeant4_DIR=<your Geant4 install path>/lib[64]/Geant4-V.m.n <path-to-source>
  (V.m.n is the version of Geant4, eg. Geant4-9.6.0)
> make
> make install

Repalce mpicxx with your MPI-compiler wrapper