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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 - Enable the following UI command : 
   
         /process/had/particle_hp/use_Wendt_fission_model true
	 
       to use the alternative Wendt fission model contained within the
       NeutronHP model for simulating fission events
       (else, the default fission model will be used).
							       
   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 (after eventually
     the above UI command to use the alternative Wendt fission model):
     
       /run/beamOn
     
   D - BATCH
     Use the macro batch.in :
     
       ./FissionFragment batch.in

 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.
 

