Geant4 8.1 Release Notes
June 30th, 2006

The code and binary libraries for the supported systems are available through our Source Code Web page.

Please refer to the Geant4 User Documentation for further information about using Geant4.


  1. Supported and Tested Platforms
  2. AIDA and CLHEP
  3. Known Run-Time Problems
  4. Compilation Warnings
  5. Known Run-Time Warnings
  6. Items for migration of the user code
  7. Geant4 Software License
  8. Detailed list of changes and fixes

1. Supported and Tested Platforms

Official platforms: More verified configurations: Platforms configured but not tested and not supported:


Geant4 8.1 requires the installation of CLHEP.
Tests have been performed with CLHEP-
The software has been verified also with CLHEP-

Geant4 8.1 examples with histogramming cowork with AIDA 3.2.1 implementations. These include: AIDA headers can be downloaded from:

3. Known Run-Time Problems and Limitations

For a complete list of outstanding run-time problems and to submit any problem you may find running this version of Geant4, please refer to the Geant4 Problem Reporting System.

4. Compilation Warnings

There may be compilation warnings on some platforms. We do not believe that any will lead to incorrect run-time behaviour.

5. Known Run-Time Warnings

The following message can be written to error output while tracking. We believe it does not give rise to incorrect behaviour.
    G4PropagateInField: Warning: Particle is looping 
    -  tracking in field will be stopped. 
       It has performed 1000 steps in Field while a maximum of 1000
       are allowed. 

6. Items for migration of the user code

Some migrations may be necessary for advanced uses of features in Geant4 in order to upgrade from release 8.0 to release 8.1. Note that a full reinstallation of libraries (or a full recompilation) and a recompilation of user applications is required.

Standard Electromagnetic physics

Some improvements are introduced to multiple scattering. As a consequence of these changes in the model, the following applies in this release: It has been reintroduced the option to utilise smaller cuts in vicinity of the geometrical boundary. The subcutoff option has been verified for a number of simplified sampling calorimeter setups. The simulation of ionization for ions was also improved. The data from NIST databases for protons and helium ion and ICRU73 data for the carbon ion are included for the first time. An interface to add user data on stopping power for particular ion in particular media is provided.
A new version of the Synchrotron radiation is released.
The user interfaces allowing to set/access EM options, cross sections and stopping powers are extended and improved.

Hadronic physics: Bertini Cascade

In this release, the G4BERTINI_KAON conditional assembly flag has been removed from the Bertini Cascade code, so that it is no longer needed for the user to set them to instruct Bertini handling of strange particles.

Physics Lists

Physics lists are updated in order to utilize recent developments in hadronic and electromagnetic physics. In particular, the more advanced model sampling of capture of negatively charged hadrons at rest is used. The new elastic process combining available models of elastic scattering is introduced with significant improvement of elastic scattering on hydrogen; the Binary and Bertini cascade developments are also utilized.

7. Geant4 Software License

As from this release, a new Software License applies to the Geant4 code. The details and the list of copyright holders is available at and also in a text file LICENSE distributed with the source code.

8. Detailed list of changes and fixes

These are the main new features/fixes included in this release since the last patched public release (for the detailed list of fixes/additions, please refer to the related History files provided in most packages):


Electromagnetic Processes (Low-energy)

Electromagnetic Processes (Standard)


General Processes: Management, Cuts, Optical



Graphical Representations


Hadronic Processes

Parameterisation Models



Track and Tracking



Physics lists

Data sets