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     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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   User application developed on the basis of example 'Hadr04', described below.
   
   Through this application an isotropical neutron source of 2 MeV is simulated
   in order to generate the neutron-induced image of an object on a detector 
   screen.



                            Hadr04
                            ------

   This example is focused on neutronHP physics, especially neutron transport,
   including thermal scattering.
   See A.R. Garcia, E. Mendoza, D. Cano-Ott presentation at G4 Hadronic group
   meeting (04/2013) and note on G4NeutronHP package
	
 1- MATERIALS AND GEOMETRY DEFINITION
 
   It is a single box representing a 'quasi infinite' homogeneous medium.
   Two parameters define the geometry :
 	- the material of the box,
	- the (full) size of the box.
 	
   The default geometry (1 m3 of pressurized water) is built in 
   DetectorConstruction, but the above parameters can be changed interactively 
   via commands defined in DetectorMessenger.
   
   A function, and its associated UI command, allows to build a material
   directly from a single isotope.
   
   To be identified by the ThermalScattering module, the elements composing a
   material must have a specific name (see G4NeutronHPThermalScatteringNames.cc)
   Examples of such materials are build in DetectorConstruction.
 	
 2- PHYSICS LIST
   
   Only processes of neutronHP package are registered : neutronElastic 
   (including thermalScattering), neutronInelastic, nCapture; nFission.
   See class NeutronHPphysics. 
   No other hadronic nor electromagnetic processes are registered.
   
   A command allows to select or not ThermalScattering model.
 
   Several hadronic physics options are controlled by environment variables.
   To select them, see Hadr04.cc
   
   NB. class NeutronHPphysics can be reused with other physicsConstructors,
   as neutron processes are deleted before to be re-created.	
	 
 	 
 3- AN EVENT : THE PRIMARY GENERATOR
 
   The primary kinematic is a single particle randomly shooted at the 
   centre of the box. The type of the particle and its energy are set in 
   PrimaryGeneratorAction (neutron 2 MeV), and can be changed via the G4 
   build-in commands of ParticleGun class (see the macros provided with 
   this example).
 	
 4- PHYSICS

   All secondaries are killed in StackingAction. Therefore an event consists of
   the transport of the primary neutron. Then one survey the thermal and non
   thermal part of this parcours.


 5- HISTOGRAMS
         
   The test contains 7 built-in 1D histograms, which are managed by
   G4AnalysisManager and its Messenger. The histos can be individually 
   activated with the command :
   /analysis/h1/set id nbBins  valMin valMax unit 
   where unit is the desired unit for the histo (MeV or keV, etc..)
   (see the macros xxxx.mac).
   
            1   "incident neutron: nb of collisions above 1 eV"
            2   "incident neutron: total track length above 1 eV"
            3   "incident neutron: time of flight above 1 eV"
            4   "incident neutron: nb of collisions below 1 eV"
            5   "incident neutron: total track length below 1*eV"
	    6   "incident neutron: time of flight below 1 eV"
            7   "incident neutron: energy distribution below 1*eV"   
      
   The histograms are managed by the HistoManager class and its Messenger. 
   The histos can be individually activated with the command :
   /analysis/h1/set id nbBins  valMin valMax unit 
   where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
   
   One can control the name of the histograms file with the command:
   /analysis/setFileName  name  (default Hadr04)
   
   It is possible to choose the format of the histogram file : root (default),
   xml, csv, by using namespace in HistoManager.hh
       
   It is also possible to print selected histograms on an ascii file:
   /analysis/h1/setAscii id
   All selected histos will be written on a file name.ascii (default Hadr04) 
 	 				
 6- VISUALIZATION
 
   The Visualization Manager is set in the main().
   The initialisation of the drawing is done via the commands
   /vis/... in the macro vis.mac. To get visualisation:
   > /control/execute vis.mac
 	
   The detector has a default view which is a longitudinal view of the box.
   The tracks are drawn at the end of event, and erased at the end of run.
	
 7- HOW TO START ?
 
   Execute Hadr04 in 'batch' mode from macro files :
 	% Hadr04   run01.mac
 		
   Execute Hadr04 in 'interactive mode' with visualization :
 	% Hadr04
	Idle> control/execute vis.mac
 	....
 	Idle> type your commands
 	....
 	Idle> exit
	
 Macros provided in this example:
  - graphite.mac: neutron (2 MeV) in graphite
  - run01.mac: neutron (2 MeV) in Water_ts
    
 Macros to be run interactively:
  - debug.mac: neutron (2 MeV) in Water_ts
  - vis.mac: To activate visualization