GPS-defined sources weight

Particles, Track, Event, Run and Biasing
1

I have used the GPS way of defining a radioactive source, isotropic; resulting in a very small number of particles actually entering the detector’s sensitive region, how should this be weighted in the GPS definition?

my GPS is :

# beam 1
# default intensity is 1 now change to 5.
/gps/source/intensity 5.
/gps/particle gamma

/gps/pos/type Volume
/gps/pos/shape Cylinder
/gps/pos/centre 0. 0. 10. cm
/gps/pos/radius 10. cm
/gps/pos/halfz 10. cm

# angular distribution
/gps/ang/type iso

# energy distribution
/gps/ene/mono 1.33 MeV



# beam 2
# twice the instensity of beam 1
/gps/source/add 10.
/gps/particle gamma

# source
/gps/pos/type Volume
/gps/pos/shape Cylinder
/gps/pos/centre 0. 0. 10. cm
/gps/pos/radius 10. cm
/gps/pos/halfz 10. cm

# angular distribution
/gps/ang/type iso

# energy distribution
/gps/ene/mono 1.17 MeV

looking forward to reply

2

Hi @chenshanhong,

Thank you for your post.

The documentation on the General Particle Source (GPS) (link), along with the extended examples (link), may provide some useful guidance.

However, please keep in mind that the gamma rays from Co-60 are correlated (link), and depending on the level of precision you need, a composite GPS setup may not be sufficient.

For simplicity, I recommend using GPS to generate Co-60 and letting Geant4 handle the decay. You can refer to this example using the radioactive decay module: rdecay01.

Best regards,
Alvaro