//$Id$

///\file "electromagnetic/TestEm13/.README.txt"
///\brief Example TestEm13 README page

/*! \page ExampleTestEm13 Example TestEm13

  How to compute cross sections from the transmition coefficient
  ( see below, \ref TestEm13_s4).
  
\section TestEm13_s1 GEOMETRY DEFINITION
 
  It is a single box representing a layer of finite thickness of
  homogeneous material.
  Two parameters define the geometry :
   - the material of the box,
   - the (full) size of the box.
   
   The default geometry (1 cm of water) is constructed in 
  DetectorConstruction, but the above parameters can be changed 
  interactively via the commands defined in DetectorMessenger.
   
\section TestEm13_s2 PHYSICS LIST
 
  The physics list contains the standard electromagnetic processes.
  In order not to introduce 'artificial' constraints on the step size, the
  multiple scattering is not instanciated, and all processes are
  registered as discrete : there is no continuous energy loss.  
    
\section TestEm13_s3 AN EVENT : THE PRIMARY GENERATOR
 
  The primary kinematic consists of a single particle starting at the edge
  of the box. The type of the particle and its energy are set in 
  PrimaryGeneratorAction (1 MeV gamma), and can be changed via the G4 
  build-in commands of G4ParticleGun class (see the macros provided with 
  this example).
   
\section TestEm13_s4 PHYSICS
 
  An event is killed at the first step of the incident paticle.
  Either the particle has interacted or is transmitted through the layer.
  The cross section, also called absorption coefficient, is computed from 
  the rate of unaltered transmitted incident particles.
  
  The result is compared with the 'input' data, i.e. with the cross
  sections stored in the PhysicsTables and used by Geant4.
   
  A set of macros defining various run conditions are provided.
  The processes are actived/inactived in order to survey the processes 
  individually.

            
\section TestEm13_s6 VISUALIZATION
 
   The Visualization Manager is set in the main () (see TestEm13.cc).
   The initialisation of the drawing is done via the commands
   /vis/... in the macro vis.mac. To get visualisation:
\verbatim
> /control/execute vis.mac
\endverbatim
   
   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.
  
\section TestEm13_s7- HOW TO START ?
 
  - Execute TestEm13 in 'batch' mode from macro files :
\verbatim
% TestEm13   compt.mac
\endverbatim
     
  - Execute TestEm13 in 'interactive mode' with visualization :
\verbatim
% TestEm13
Idle> control/execute vis.mac
....
Idle> type your commands
....
Idle> exit
\endverbatim
 
  
*/
