Hello!
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?
please, take $G4INSTALL/examples/extended/hadronic/Hadr01
Do not change code but prepare macro file with your material and cube sizes and repeat computations for two Physics Lists. You do not need very high statistics , may be 1000 will be enough. This is take few minutes and you will see are your results compatible with Hadr01 results.
Dear Vladimir, thank you for your advice. I created a macro, file attached, and I have this output both for QGSP_BIC and for QGSP_BIC_HP:
Beam particle Ca48
Beam Energy(MeV) 242
Number of events 1000000
Average energy deposit (MeV) 242 RMS(MeV) 0
Average number of steps 1
Average number of gamma 0
Average number of e- 0
Average number of e+ 0
Average number of neutrons 0
Average number of protons 0
Average number of antiprotons 0
Average number of pi+ & pi- 0
Average number of pi0 0
Average number of kaons 0
Average number of muons 0
Average number of deuterons+tritons 0
Average number of He3+alpha 0
Average number of ions 0
Average number of forward neutrons 0
Average number of reflected neutrons 0
Average number of leaked neutrons 0
Average number of proton leak 0
Average number of pion leak 0
If I set in macro 20 GeV proton as primary particle - I get some results on the average number of particles.
Can you please help with my macro?
Thank you! hadr01BIC.txt (581 Bytes)
I found a mistake myself - my cuts were too high and I forgot # before the physics list command. With cuts 0.0001 mm for 1000 ions of Ca I get for QGSP_BIC
Average number of gamma 2.838
Average number of e- 3.417e+04
Average number of e+ 0
Average number of neutrons 0
And for QGSP_BIC_HP:
Average number of gamma 9.39
Average number of e- 3.431e+04
Average number of e+ 0.001
Average number of neutrons 0.007
There is a discrepancy, but much smaller than mine.
I redo my counting method and check cuts, thank you.
I recalculated hadr01 with a default cut value (0.7 mm) for two lists for 10000 ions of 48Ca.
For QGSP_BIC_HP:
Average number of steps 56.28
Average number of gamma 6.007
Average number of e- 19.55
Average number of e+ 0.0008
Average number of neutrons 0
For QGSP_BIC:
Average number of steps 1.032
Average number of gamma 0.0038
Average number of e- 0.0081
Average number of e+ 0.0001
Average number of neutrons 0.0011
3 orders of difference for gamma and electrons. Here are my macro files: hadr01BIC.txt (579 Bytes) hadr01BIC_HP.txt (581 Bytes)