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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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FissionFragment Example
B.Wendt
brycen.linn.wendt@cern.ch
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This example demonstrates an application of the fission fragment model in the
NeutronHP model. This example is capable of using both models, but is designed
around the Wendt Fission Model. A warning will be shown if the environment
variable that enables the Wendt fission model is not set.
1 - EXECUTION
A - ENVIRONMENT
G4NEUTRONHP_PRODUCE_FISSION_FRAGMENTS - REQUIRED
The example requires this enviroment variable to be set. An error will be
displayed and the example will terminate if this environment variable is
not set.
G4NEUTRON_HP_USE_WENDT_FISSION_MODEL - OPTIONAL
This environment variable enables the Wendt fission model contained
within the NeutronHP model for simulating fission events. The default model
will be used otherwise. A warning will be displayed if this environment
variable is not set.
B - COMMAND LINE ARGUMENTS
The example can be run without any input arguments. However, a few options
are available:
-i ARG : run in batch mode from script file ARG
-o ARG : write output to file ARG
(defaults to FF_Neutron_HP.out)
-n ARG : multithreading with ARG number of threads
(only works if Geant4 was compiled with multithreading
enabled)
No output is currently generated, although the argument is provided. It is
anticipated that future versions will provide some form of output
summarizing the results of the simulation.
C - INTERACTIVE
No specialized UI commands are currently provided.
To run the simulation, use the standard UI command:
/run/beamOn
2 - GEOMETRY
The geometry is constructed in the FFDetectorConstruction class. The setup is
based on a subcritical assembly design.
A - MATERIALS
This example requires a number of materials. They are loaded or constructed
in the "DefineMaterials" function. A few of the materials are obtained from
the NIST database (ref. Geant4 User's Guide for Application Developers,
Appendix: Geant4 Materials Database). These materials are:
- Air
- Aluminum
- Graphite
- Polyethylene
- Stainless steel
- Water
Not all of the necessary materials were available from the NIST database,
and were constructed manually from the estimated isotopics. These materials
are:
- 20% U235 enriched uranium
- 93% B10 enriched BF3
B - Volumes
The world is composed of air instead of a vacuum to provide room return.
The subcritical assembly is a water-filled aluminum tank.
The fuel plates are composed of aluminum-clad uranium meat, and are
completely submersed in the water of the subcritical assembly.
An AmBe neutron source is placed in the exact center of the fuel plate
loading configuration. The material is currently modeled as steel until
more exact specifics of the AmBe isotopics can be obtained.
The subcritical assembly rests on top of a graphite pile for moderation and
shielding.
3 - PHYSICS LIST
The particle's type and the physic processes which will be available
in this example are set in the QGSP_BIC_HP physics list.
4 - PRIMARY GENERATOR
The primary generator is defined in the FFPrimaryGeneratorAction class.
The default particle is a 4.5 MeV neutron originating from the
"NeutronSource" volume. The particles initial direction is isotropically
sampled.
5 - DETECTOR RESPONSE
The scoring method is yet to be implemented, although the BF3 detector is
already included in the detector construction.
6 - VISUALISATION
An example "vis.mac" will be included in a future release. For now, please
refer to other examples for a few suggestions.
Gabriele Cosmo