|Message: Bias in target but not in detector||Not Logged In (login)|
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The issue I'm currently working on is wanting to bias a certain physics process in my target for a fixed target simulation, but have no bias for the rest of the simulation as the shower evolves in the detector.
I want to bias G4eplusAnnihilation to get a 5 GeV positron beam hitting a liquid hydrogen target to always result in 2 gamma annihilation. Currently I modified the G4EmStandardPhysics.cc file to include a bias on this process before adding it to a G4VModularPhysicsList. Since the beam is much more energetic, I tried to place an energy cut at around 4.8 GeV so that this process of e+e- -> 2gamma doesn't show up incredibly biased--or at all in this case--in the detector built of may CsI crystals.
I've tried changing the cuts on the model, but when compiling, Geant doesn't recognize the model. Perhaps this is a consequence of the model being immediately invoked? (G4eeToTwoGammaModel)
I also tried changing the physical properties of the target, but of course that biased all the processes by the same factor and did not give me the desired result.
Ultimately I want to have a 2gamma event every time I turn on the beam, and have all other normal EM processes occur in my detector.
Is there a good way of going about this?