I’m creating a model in Geant4 10.7p01 on CentOS 7.0 in order to estimate the number of created secondaries after the implantation of 242 MeV 48Ca in copper. The calculation is conducted on a server with 56 threads in multithreading mode. It’s the first step of estimation of absorbed energy of secondaries in coils of a superconducting magnet.
My geometry is simple: 10 cm cube of copper in a vacuum. I count a number of escaped neutrons, gamma, protons, and electrons from this copper cube in vacuum volume. I use copper material from the NIST database and G4_Galactic for vacuum.
I do counting this way:
I have several sets (std::set) of trackID for each particle sort contained in EventAction. I clear these sets in EndOfEventAction. In SteppingAction I check the sort of particle (I use the name from ParticleDefinition) and logical volume of step. If the volume is a vacuum, I check if I already have this trackID in the corresponding set. If I don’t have it, I add one to the counter of this particle sort in RunAction, and I add trackID in the set. I found this way of counting in this topic.
I don’t create my own physics list, I use QGSP_BIC and QGSP_BIC_HP. I set physics list in my main function with this command: runManager->SetUserInitialization(new QGSP_BIC()); I don’t add any other physics.
And here is the problem. I have a large discrepancy in the number of created secondaries for these two physic lists.
For 1e8 of primary particles with QGSP_BIC I have: 2.2e5 gamma, 1.1e5 neutrons, 6.1e3 protons, 3.1e3 electrons and 6.1e3 some other particles.
For 1e8 of primary particles with QGSP_BIC_HP I have: 3.2e8 (!) gamma, 1.2e5 neutrons, 6.9e3 protons, 2.9e7 (!) electrons and 2.1e8 some other particles.
Same type of calculation is conducted in FLUKA. Results: 0.54e5 gamma, 0.59e5 neutrons, 2.5e3 protons and 0.44e3 electrons.
The discrepancy between FLUKA and QGSP_BIC is less than an order of magnitude - seems good enough (or is it?) for such type of calculation. But the discrepancy between the two physics lists in the number of gamma and electrons is huge.
What can be possible reasons for it?
Thank you for your help!