As a GATE user, we commonly use “sources” in our simulation as, plainly speaking, the part which generates the primary particle where and how we want. On the other hand, there is no such thing as a “source” in Geant4 because this concept is only introduced in GATE. As GATE developers, we need to understand what a “source” actually is and how it relates to Geant4. To this end, it is important to understand the mechanism of generating primary particles in Geant4.
As a GATE user, we commonly use “sources” in our simulation as, plainly speaking, the part which generates the primary particle where and how we want. On the other hand, there is no such thing as a “source” in Geant4 because this concept is only introduced in GATE. As GATE developers, we need to understand what a “source” actually is and how it relates to Geant4. To this end, it is important to understand the mechanism of generating primary particles in Geant4.
See this doc.