Example FissionFragment

Table of Contents

• EXECUTION
  • ENVIRONMENT
  • COMMAND LINE ARGUMENTS
  • INTERACTIVE
  • BATCH
• GEOMETRY
  • MATERIALS
  • VOLUMES
• PHYSICS LIST
• PRIMARY GENERATOR
• DETECTOR RESPONSE
• VISUALISATION

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.

---

EXECUTION

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.

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.

INTERACTIVE

No specialized UI commands are currently provided.

To run the simulation, use the standard UI command:

  /run/beamOn

BATCH

Use the macro batch.in :

  ./FissionFragment batch.in

GEOMETRY

The geometry is constructed in the FFDetectorConstruction class. The setup is based on a subcritical assembly design.

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. These materials are:

• Air
• Aluminum
• Graphite
• Polyethylene
• Stainless steel
• Water

For more information, visit: Geant4 User's Guide for Application Developers, Appendix: Geant4 Materials Database

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

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.

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.

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.

DETECTOR RESPONSE

The scoring method is yet to be implemented, although the BF3 detector is already included in the detector construction.

VISUALISATION

An example "vis.mac" will be included in a future release. For now, please refer to other examples for a few suggestions.

---

Author

B. Wendt (bryce.nosp@m.n.li.nosp@m.nn.we.nosp@m.ndt@.nosp@m.cern..nosp@m.ch)

Date

June 26, 2014