|Message: Muon-induced nuclear reactor in Geant4 10?||Not Logged In (login)|
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|I'm seeing a strange thing when using Geant4 10.00 (both with p02 and p04). While simulating the passage of muons through an uranium target my simulation sometimes gets stuck. Investigating a bit deeper I found that the simulation actually runs, but that the event never finishes since many slow neutrons are generated inside the uranium, and they in turn induce some fission reactions which generate other neutrons and so on. The process looks similar to a "nuclear fission reactor". Typically, the reactor is ignited by a stopping muon or by a gamma. I see this behaviour very frequently compared to what one can reasonably expect: when running 10 instances of my simulation program, each one simulating 10^5 muons, typically one or two of them get stuck because of this mechanism. I didn't see anything like this when I was using 9.6.p02: I simulated an amount of muons of the order of 10^9 without ever encountering such a behaviour. So I think that something in the physics of fission and of thermal neutron changed in version 10, and that this change might be a breakage. I can provide some detail if required, but while I am able to reproduce this behaviour I could not produce a simplified geometry/simulation that shows off the same issue. Thanks.|
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