
               *******************
               ***  MANDATORY  ***
               *******************

 Visualize one event:

   Idle> /run/beamOn 1

 that shows the case of a geantino, being the default
 choice in class MyPrimaryGeneratorAction.

 --- PHYSICS : add charged geantino in order to visualize
               bending of the trajectory due to the magnetic field.
               Use the following commands:

                 Idle> /gun/particle chargedgeantino
                 Idle> /run/beamOn 1  

