To compile and run Geant4 under Windows systems, some additional information and tools are required, although the installation produre is similar to that required on a UNIX based system. On Windows, the Cygwin toolset and the Microsoft Visual C++ compiler are used. Cygwin32 is a UNIX development environment available for Microsoft Windows. You can freely obtain Cygwin32 from Cygwin or Cygwin/X . We do not support direct use of Visual Studio; i.e. we do not provide Visual Studio workspace (.dsw) or project (.dsp) files, nor we do provide makefiles for the nmake application of MS Visual C++. We use several of the tools provided by the Cygwin toolset: make.exe as a make tool g++.exe as a tool to analyse source file dependencies and create dependency (.d) files several other unix tools like cp, mv, rm, touch, etc. At the installation of the Cygwin toolset it is therefore required to explicitely select some packages (i.e. gmake, gcc, binutils and tcsh from the "devel" category) in addition to those which are part of the default installation. For more details on the toolset, please see the documentation available on the Cygwin pages . The User's Guide has quick start guides and help with setting up Cygwin with setup.exe. Links to some installation tips for the Cygwin toolset and also "step by step" installation guides can be found in the section Appendix - Step-by-Step Installation Guides - Build for MS Visual C++ of Geant4 User's Guide - For Application Developers. The usage of Cygwin32 for the build environment results in a build procedure similar to that on a UNIX system. The following steps are required to install geant4: Install Cygwin (see also notes above and additional installation notes for known issues related to the most current version): We do not depend on any specific feature of the version of Cygwin, so newer versions (or slightly older) are expected to work. Set the environment for MS Visual C++, i.e. set the paths to libraries, include files, and executables for MS Visual C++. This can be done by modifying the start-up batch file cygwin.bat of Cygwin32 to include all the MSDOS commands found in the file vcvars32.bat provided in MS Visual C++ (in the VC++ .NET compiler installation directory, and usually located inside the Common7/Tools directory). This modification should be done after the installation of the Cygwin toolset, so that the environment gets properly set at the time of the invocation of the shell. Unpack the source code into a directory of your choice. Start the Cygwin shell from the start menu. At this point you're ready to install Geant4. If manual installation is chosen, you must set the necessary environment variables. There are various ways to do so; for example through a command file for the Cygwin bash shell. This command file could be named geant4-setup.sh, and you must execute it with . geant4-setup.sh including the leading dot and blank space. You could also have this as your .bashrc file. The commands in the command file should be: # Set G4SYSTEM export G4SYSTEM=WIN32-VC # # Set Path to CLHEP export CLHEP_BASE_DIR=C:/usr/local # # --- Other optional settings #Turn on verbose to show command used for compilation #export CPPVERBOSE=1 # Note, in the example above, CLHEP was installed in C:/usr/local, therefore include/CLHEP and lib/CLHEP.lib must be included therein. Once the environment is correctly set, the libraries are built using make from the geant4/source directory typing make from the Cygwin bash shell prompt. Examples can be built in the same way as the libraries from examples/novice/N01, for instance: type make from the shell prompt. Note that, depending on which external software is used, there may be some warnings in linking about conflictings libraries. This often seems to be caused by an external library compiled for a different run time environment. The binary of the example is placed by default into the geant4/bin/WIN32-VC directory. You may run it either from this directory or from the examples/novice/N01 directory; sample input and output files are placed in each of the examples/novice directories. Some of the examples will need to read data files, and the place has to be given in environment variables again similar to the following example: # # Environment variables needed to find geant4 data files: # # Data for neutron scattering processes, # distributed in a separate tar file, then placed under data export G4NEUTRONHPDATA=c:/usr/local/geant4/data/G4NDL # # Nuclear Photon evaporation data, # distributed with the source files under data export G4LEVELGAMMADATA=c:/usr/local/geant4/data/PhotonEvaporation # # Data for radiative decay hadronic processes under data, # distributed in a separate tar file export G4RADIOACTIVEDATA=c:/usr/local/geant4/data/RadiativeDecay # # Data for low energy electromagnetic processes, # distributed in a separate tar file, then placed under data export G4LEDATA=c:/usr/local/geant4/data/G4EMLOW # # Data for nuclear shell effects for INCL/ABLA hadronic model, # distributed in a separate tar file, then placed under data export G4ABLADATA=c:/usr/local/geant4/data/G4ABLA # # Data for measured optical surface reflectance in optical processes, # distributed in a separate tar file, then placed under data export G4REALSURFACEDATA=c:/usr/local/geant4/data/RealSurface # All compiler and linker options are set in config/sys/WIN32-VC.gmk. If you require options different from our choice, you can modify this file. DLLs (Dynamic Link Libraries) on Windows are supported for MS-VC++ and can be built for the compound kernel libraries of Geant4 (see of the Installation Procedure of this Guide for a dissertation on global/compound libraries). The libraries can be built either manually, issuing the command: make dll from the directory $G4INSTALL/source or by specifying it through the Configure script used for the installation. Then, to build any application making use of the installed DLLs, the environment variable G4LIB_USE_DLL must be set in the environment. Once the application is built, it is required to specify to the system the path where the DLLs are installed. To do so, add the absolute path (in Cygwin format) of the DLLs installation directory to the PATH variable; for example: export PATH=$PATH:/usr/local/geant4/lib/$G4SYSTEM You may then be able to run successfully your application.