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4.1. USING GAMOS GENERATOR
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To choose an isotope as particle source you have to use the command:
/gamos/generator/addIsotopeSource SOURCE NAME
ISOTOPE NAME ACTIVITY
SOURCE NAME is the name of this source, that you have to use if you
want later to change its time, energy, position or direction distribution.
ISOTOPE NAME is one of the isotopes read from the input file,
ACTIVITY is the activity you want to set for that isotope2 .
You may choose several isotopes by repeatedly writing this command.
This command triggers the reading of the file named “isotopes.dat”
if it has not been read yet. You may change the name of this file with the
command
/gamos/setParam Generator:Isotope:FileName MY FILENAME
To learn how to change the directory list where GAMOS looks for this file,
please read the section “Managing the input data files”.
If you don’t change any property the particle will be generated with a
time distribution of type “Decay”(see below), energy distribution of type
“constant isotope decay” (see below), position at (0,0,0) and random direction.
Time distributions
• Constant time
/gamos/generator/timeDist SOURCE NAME
GmGenerDistTimeConstant TIME
All the primary particles will be generated at time 0. If you want to
set it at a different time, you can add the extra parameter TIME.
• Decay time
/gamos/generator/timeDist SOURCE NAME
GmGenerDistTimeDecay ACTIVITY
The primary particles will be generated with a time following a typical
decay distribution, with the activity of the particle source. To be concrete the time is sampled with a Poisson distribution that is obtained
as follows:
rnd poiss = -(1.0/ (activity/second) ) * log(RandFlat::shoot());
the activity is given by the parameter ACTIVITY.
Energy distributions
• Constant energy
2
The available units in Geant4 are becquerel and curie