Hi Physics experts,
I was curious if folks could explain how the Q-value of a reaction is calculated when using the ParticleHP inelastic physics when only the total inelastic cross-section data and no information on a specific reaction channel is provided.
I’ve been able to see that when the Q-value for a specific FS number is provided, this is used for further reaction kinematics, but I can’t quite figure out where the Q-value is coming from if there is no channel specific data.
I may be confused by your question as Q values depend on the at rest mass of the reactants or products. These are tabulated in ENDSF and other libraries used by Geant (and easily navigable using the NNDC website). Those values look at the ground state only. If you are considering excited states such as some alpha decays or many gamma decays, then you just “add” the energy of the state to the right hand side. However, the these states are just branches of the reaction cross section anyway. So there is a lot to the tree there. First checking if an inelastic reaction occurs at all, then if it does, what is the channel then to what state, etc.