Bug in radioactive decay for neutron?

Dear Geant4 experts,

I am running into a Geant4 crash in my application, where we want to simulate C-N-O nuclei interactions in our detector.

First, the error message:

G4DecayTable::SelectADecayChannel :: no possible DecayChannel neutron
-------- EEEE ------- G4Exception-START -------- EEEE -------
*** G4Exception : DECAY003
issued by : G4Decay::DoIt
Can not determine decay channel for neutron
mass of dynamic particle: 0.933405 (GEV)
dacay table has 1 entries
0: BR 1, IsOK? 0, --> e- + anti_nu_e + proton

*** Fatal Exception *** core dump ***
G4Track (0x55d8264583c0) - track ID = 575, parent ID = 1
Particle type : neutron - creator process : ionInelastic, creator model : Binary Cascade
Kinetic energy : 0 eV - Momentum direction : (1,0,0)
Step length : 0 fm - total energy deposit : 0 eV
Pre-step point : (-649.462,199.77,571.331) - Physical volume : BattaryA_physical (mat_Battery)
- defined by : not available
Post-step point : (-649.462,199.77,571.331) - Physical volume : BattaryA_physical (mat_Battery)
- defined by : not available
*** Note: Step information might not be properly updated.

-------- EEEE -------- G4Exception-END --------- EEEE -------

We are using Geant4.10.05p01. This exception arises randomly on some events when the primary particle is Carbon-12, Carbon-13, Nitrogen-14, Oxygen-16, and potentially others (untested). The physics list is FTFP_BERT.

The same issue was also observed by a colleague on Geant4.10.03p02. In his benchmarks, the crash probability is very high in the energy range of 10-100GeV. (E.g. 40% failure rate for Nitrogen-14 at 10k events per file) but he didn’t find such crashes at energies above 100 GeV.

I found the same error message on the HyperNews forums: http://hypernews.slac.stanford.edu/HyperNews/geant4/get/hadronprocess/1588/3.html but it seems the issue was not fixed.

Do you know what’s wrong?


it seems that there is nothing wrong in your application but in your setup you have larger probability to get this bug conditions.
The bug may be already fixed, next week a new public Geant4 version 10.6beta will be available. Please, try it out.

If the bug still present, please, fill bug report in the Bugziila: https://bugzilla-geant4.kek.jp/

You may copy this text for the bug report and in order to help fixing put maximal number of details about primary state, energy and the target.


Dear Vladimir,

Thank you for your reply. We tested the beta of 10.6 and the bug is still present. I filled a bug report in Bugzilla (problem #2175)

The issue will be traced in Bugzilla.