
///\file "exoticphysics/ucn/.README.txt"
///\brief Example ucn README page

/*! \page Exampleucn Example ucn

\author Peter Gumplinger - TRIUMF, Vancouver, Canada \n
 gum@triumf.ca

This example demonstrates how ultra-cold neutrons (UCN) propagate
in a guilde and how this can be simulated in Geant4.

\section ucn_s1 INTRODUCTION

This example exhibits the functionality of UCN physics


\section ucn_s2 GEOMETRY

  The geometry consists of a single hollow pipe (cylinder)
  placed in a world.

  Default World Size: G4Box - 1m x 1m x 100m

  The pipe wall is made of G4_Ni while the world and, hence,
  the inside of the pipe is made from G4_Galactic

  The G4UCNMaterialPropertiesTable properties are:
\verbatim
  "REFLECTIVITY" = 1
  "DIFFUSION" = 0.1
  "FERMIPOT" = 252.0 neV
  "SPINFLIP"= 0.
  "LOSS" = 12.5e-5
  "LOSSCS" = 0.
  "ABSCS"= 4.49    // 1/v loss cross-section  at room temp.
  "SCATCS" = 18.5  // (incoherent) "elastic" scattering cross-section
\endverbatim

  The MicroRoughnessParameters are:
\verbatim
  Roughness correlation length w = 30nm
  Surface roughness b = 1nm
  # of angles theta_i in the look-up tables: 180
  # of energie bins in the look-up tables: 1000
  min. and max. values of theta_i: 0*degree and 90*degree
  min. and max values of Energy: 1neV and 1000neV
  # of angles theta_o in the look-up table calculation: 15
  # of angels phi_o   in the look-up table calculation: 15
  angular cut: 0.01*degree
\endverbatim

  The default step limits in the vacuum is 1mm and maxTime is 100s

  The simulation is in a G4UniformGravityField

\section ucn_s3 PHYSICS LIST

  The ExUCNPhysicsList defines only 
  - G4Neutron, G4Proton, G4Electron, G4AntiNeutrinoE, G4MuonPlus, G4MuonMinus and 
    G4GenericIon

  Through ExUCNExtraPhysics the following processes are instantiated:
  -  G4StepLimiter
  -  G4UserSpecialCuts

  and in ConstructUCN()
  -  G4UCNLoss
  -  G4UCNAbsorption
  -  G4UCNMultiScattering

\section ucn_s4 THE PRIMARY GENERATOR

  The primary kinematic consists of a single ultra-colde neutron 
  (uniform between 1neV and 100neV from the origin uniform into 4pi

  A RUN is a set of events.


\section ucn_s5 VISUALIZATION

  The Visualization Manager is set in the main () (see ExUCN.cc)
  for interactive session.
  The initialisation of the drawing is done via the command
    
\verbatim
/control/execute vis.mac
\endverbatim

\section ucn_s6 TESTING

   This example handles the program arguments in a new way.
   It can be run with the following optional arguments:

\verbatim
% ExUCN [-m macro ] [-u UIsession] [-t nThreads]
\endverbatim

  The -t option is available only in multi-threading mode
  and it allows the user to override the Geant4 default number of
  threads. The number of threads can be also set via G4FORCENUMBEROFTHREADS
  environment variable which has the top priority.

  Execute ExUCN in 'batch' mode from macro files e.g.

\verbatim
% ExUCN -m ExUCN.in > ExUCN.out &
\endverbatim

  Execute ExUCN in 'interactive' mode with visualization e.g.

\verbatim
% ExUCN
Idle> type your commands, for example:
Idle> run/beamOn 1
...
\endverbatim

\section ucn_s7 HISTOGRAMS

  - no histograms for now
*/
