[Gate-users] Generation of multiple primaries per event with gps ?

[Luca Terray]

Dear Gate users,

I am new to this mailing list and happy to join !

I am currently trying to reproduce within Gate the cascade emission of gamma rays produced by the desexcitation of some nuclei, without using the RadioactiveDecay module (it works but it slows down the simulation). Instead I would like to describe manually the cascade. My idea is to define two (or more) sources with GPS and call them simultaneously at each event but I don't find the command for that. By default, it seems that only one primary is generated at the beginning of each event.

Therefore my question is : when using GPS to define sources in Gate, is there a way to allow the event generator to produce multiple primary particles simultaneously (i.e., within the same event) ? 

In G4, there is a GPS parameter called "multiplevertex" that you have to set true in order to allow simultaneous generation of multiple particles (default is false) but I could not find a similar command in Gate (something like /gps/source/multiplevertex true ?). Looking through documentation, I also found the source type "back-to-back" which generates two particles with directions at 180°, which is very close to what I want except that I want the directions of emission to be isotropic. 

If you have any idea of how to do that, I would greatly appreciate your help ! 

Below I paste the piece of the macro defining the source.

Many thanks in advance

Luca

#=====================================================
# SIMPLIFIED SOURCE OF 60Co (3->1 & 1->0 simultaneous)
#=====================================================
# 3->1 emission (1173 keV)
/gate/source/addSource                            sourceCobalt31 gps
/gate/source/sourceCobalt31/gps/particle          gamma
/gate/source/sourceCobalt31/gps/monoenergy        1173 keV
/gate/source/sourceCobalt31/gps/pos/type          Surface
/gate/source/sourceCobalt31/gps/pos/shape         Circle
/gate/source/sourceCobalt31/gps/pos/radius        1 mm
/gate/source/sourceCobalt31/gps/centre            0. 0. -61.32 mm
/gate/source/sourceCobalt31/setIntensity          1
# 1->0 emission (1332 keV)
/gate/source/addSource                            sourceCobalt10 gps
/gate/source/sourceCobalt10/gps/particle          gamma
/gate/source/sourceCobalt10/gps/monoenergy        1332 keV
/gate/source/sourceCobalt10/gps/pos/type          Surface
/gate/source/sourceCobalt10/gps/pos/shape         Circle
/gate/source/sourceCobalt10/gps/pos/radius        1 mm
/gate/source/sourceCobalt10/gps/centre            0. 0. -61.32 mm
/gate/source/sourceCobalt10/setIntensity          1