I activated the DISCARD card to disable proton transport in my simulation dealing with neutron activation in air around a D-T neutron generator. PU_Att.flair (6.6 KB) PU_Att.inp (6.8 KB)
I’am using 4-4.1 FLUKA version.
I get the following error:
At line 1412 of file lowneu/kasneu.f
Fortran runtime error: Index ‘0’ of dimension 1 of array ‘wlwnsc’ below lower bound of 1
Error termination. Backtrace: #0 0x7f12ff783960 in ??? #1 0x7f12ff7844d9 in ??? #2 0x7f12ff784ad6 in ??? #3 0x7f13001b9402 in kasneu_
at lowneu/kasneu.f:1412 #4 0x7f12fffe5c13 in kaskad_
at cascade/kaskad.f:4292 #5 0x7f12ffeaaed5 in feeder_
at cascade/feeder.f:270 #6 0x7f12ffe0d39b in flukam_
at main/flukam.f:2812 #7 0x7f12ffe099f0 in fluka
at main/fluka.f:77 #8 0x7f12ffe099f0 in main
at /root/rpmbuild/BUILD/fluka-4/src/usflmd.inc:15
I tryed to solve my problem setting an energy cutoffs for protons generated by neutrons using PART-THRES card. I choose an energy cutoff of 14 MeV because I notice it was the maximum energy of the protons produced (as the source neutrons). PU_att.flair (7.1 KB) PU_att.inp (7.2 KB)
Unfortunately, plotting the protons fluence inside and outside the shielding of my source, the protons are still present even if with very small values.
Hi @corrado.tine
sorry for the delay.
Concerning your first message, thanks to your input the DISCARD issue is now fixed. If you are interested, we can provide you privately with the modified object file that will allow you to run the simulation with DISCARD, in order to test the fix prior to release.
When you are running with a high PART-THR, the protons coming from neutron interactions are always generated (in order to complete the kinematics of the interaction) and pushed into the stack.
Once they are pulled from the stack to be transported. if they are below threshold they will simply range-out. So you will still see them inside the USRTRACK.
I am curious why you want to kill the protons and deuterons from your simulation?
Some other small remarks on your inputs
You are redefining the Air using the ICRU definition. I would strongly suggest to use the predefined AIR material in FLUKA which is based on the same ICRU definition and in addition if contains the proper Ionization potential and Sternheimer parameters
You are redefining the Hydrogen as H-1 and a few other elements as purely isotopic like B-10. Are you sure you want that. e.g. redefining to H-1 you will omit the deuteron content and you will not use the TSL libraries for H. In concrete, Hydrogen will be in the form of H2O so you need to take into account the binding effects, while for polyethylene you need another TSL library. For Boron are you sure you have only isotopically rich B-10 without any trace of B-11?
Dear Vasilis,
thank you for your answer and your detailed questions.
Concerning the DISCARD card: I am really happy that the issue has been fixed. Yes, of course I am interested to test the fix prior to release.
Concerning the PARTH-THR card: If I correctly understood, the protons that are generated with an energy lower than the threshold are not killed and continue to be transported. Right?
Regarding your questions:
The reasons because I want to kill protons and deuterons from my simulation is explained here: https://fluka-forum.web.cern.ch/t/difference-scoring-in-air-activation-between-fluka-and-mcnp/6341
As you can read, I am comparing the results between FLUKA and MCNP in the air activation (“INPU” and “INSHIEL” regions) by a D-T neutrons source. In MCNP I only considered the main neutron reactions because I thought they are most relevant. However, I found an important discrepancy in N-13 production and I suspect that the secondary protons can contribute. So, the simple way to check was to exclude protons and other particles from my FLUKA simulation. Actually, from the first results using PART-THR card, the value of N-13 is very close with that of MCNP. So it seems that I have solved my problem.
Regarding your other remarks:
The reason I changed some predefined material in FLUKA was to make equal the materials composition of FLUKA with MCNP ones.
Thank you for your suggestion, I will use the predefined AIR material. I incorrectly thought that the predefined AIR material was different from ICRU definition.
I defined user material in FLUKA for air, polyethylene, borated polyethylene and concrete according to the follow compendium: https://www.pnnl.gov/main/publications/external/technical_reports/PNNL-15870Rev1.pdf
because they are the standard ones used in MCNP.
I was aware that I didn’t consider the natural isotopic composition of some elements (for example, in polyethylene only H-1 is considered for hydrogen while natural composition is considered for carbon). In any case, to perfect my simulations I can include all natural composition of the elements, as you suggest.
I considered also the problem of TSL libraries and the binding effects of hydrogen in water and I decided to not activate them both in FLUKA and MCNP. The water is part of the secondary shielding (labyrinth wall) and concrete wall: I guess that these material don’t contribute so much in air activation inside the labyrinth. Do you suggest to activate them at least for polyethylene and graphite?
