Hi,
I want to simulate the neutron spectrum of 14.1 MeV neutrons in a diamond detector and use MCParticle at the moment to get the energy deposition.
But I encounter a well known issue in Geant4 that the energy deposition for all C(n, alpha) reactions is incorrect (also C(n, 3 x alpha, …). In geant4 this can be resolved by using the command
“/process/had/particle_hp/use_NRESP71_model true”
in the macro file, which was also discussed here.
When i use a macro file in allpix and add the command it does no change the outcome. Is there any ways to pass the command to the Geant4 module of allpix or any other way to fix the issue? The problem exist with all PhysicsLists.
Thanks in advance to everyone, help is much appreciated!
Hi @jmelbing
that’s an interesting problem 
Right now, we filter the macro commands to only those which alter the GPS. All other commands should generate a warning.
What you could try out directly is to change this line here: src/modules/DepositionGeant4/GeneratorActionG4.cpp · master · Allpix Squared / Allpix Squared · GitLab to allow all command to be processed.
I have to think and read G4 docs a bit to see what would make sense as additional categories to allow, but /process/ definitely seems to make sense to me. I took the freedom to include /process/ commands in this merge request.
Best regards,
Simon
@jmelbing I extended the merge request to automatically enable the model when any of the sensors is made of diamond.
Hi @simonspa
thank you very much for the fast reply and fix. The latest version works well!
Just as information for everyone who wants to simulate neutron interactions with Diamond, the default physics list “FTFP_BERT_LIV” does not yield correct results for the 12C(n,alpha)9Be reaction.
Best regards,
Julian
@simonspa Now when I think about it, maybe the model should also be automatically activated for “Silicon Carbide” because the carbon content will have the same problem as Diamond in general.
Excellent, thank you very much for the feedback - more fixes here: