HOWTO force hdgeant4 to decay particles in certain channels

Geant4 defines all of the common particles that one would want to propagate through an experimental setup as instances of the G4ParticleDefinition class. Common particle types that are derived from G4ParticleDefinition include singleton classes G4Electron, G4Positron, G4PionPlus, G4Eta, and G4JPsi. Nested under subclass G4Ions are additional singleton classes such as G4Proton, G4Neutron, G4Deuteron, G4Alpha, and G4GenericIon for any non-lived isotope with Z>4. In addition to anti-particles like G4AntiProton, there are also so-called "adjoint" particles like G4AdjointElectron and G4AdjointGamma. These adjoint particles are not anti-particles, they are introduced into the G4 framework as particles that are simulated backwards in time. These are not currently used in the GlueX simulation, but I include them in this overview for completeness.