Fragments' kinematic distribution in proton Inelastic processes from 10.2 to 10.6

20200210_G4.pdf (2.0 MB)

I was simulating the proton interacting with water, and only record the first proton inelastic process with 200MeV incident beam.
Then I was comparing the kinematic distribution of fragments generated in the proton Inelastic processes using 10.2.p3, 10.5.p1 and 10.6.

The model is G4BinaryCascade, and the cross-section I used is Gheisha.

I found the fragment yield was quite different during them in the slide(p.3).

The fragments’ angular distribution looks consistent.

However, for kinematic energy, more protons/neutrons are produced in low energy in the slide(p.4, p.5).

In particular, the emitted gamma energy distributions(p.6) are quite different during them.

I dig into the code, it looks there is a big change in FermiBreakUp(10.2->10.5) and PhotonEvaporation(10.2->10.5->10.6).

So my question is as below.

  1. The fragments’ distribution looks unstable with different versions.
    Could you help me figure out why so unstable?

  2. Is there any real data to be compared with Geant4?
    Since the distribution is different with different Geant4 version, we can not give a conclusion to say which version is better or not.

Thanks in advance.




with Geant4 10.2 faced problem that in multi-threaded mode different models responsible for simulation of radioactive decay, hadron fragmentation, nuclear gamma de-excitation, existed separately. Between 10.2 and 10.4 a significant internal revision was carried out which was continues with bug fixes in 10.5 and 10.6.

Unfortunately, there was a typo GHEISHA cross sections , which is fixed only recently in 10.6p01. Also note, that since 10.4 GHEISHA cross sections are removed from all reference Physics Lists.