Dear experts,
Hello.! I have been engaged in simulation related to residual radioactivity and have some doubts.
I used RESNUCLEi card associated DCYSCORE card to collect radioactive nuclei during the nuclear action. I also used LOW-MAT and LOW-NEUT card in the view of the neutron energy is below 20 MeV in my case. But the results is really odd. There is no radioactive nuclei produced in Material Water and CH4_Sol (Water is the default material in Fluka, and CH4_Sol is defined by myself),while this situation didn’t occur in other material(Be, V, Cu, Ag_Cu, BPE…).
The .inp file is attached there.
Thanks all.
version8.inp (29.7 KB)
Hi Yongguang,
Sorry for the late reply! I was briefly looking into your problem, let me come back to you with a more complete answer by the end of the day.
Cheers,
Jerzy
Hi again,
First of all, in the current version of FLUKA you don’t really need to set up the LOW-MAT and LOW-NEUT cards as by default with DEFUALT PRECISIO neutron point wise treatment is used for low energy neutrons:
https://flukafiles.web.cern.ch/manual/chapters/description_input/description_options/defaults.html
The lack of radioactive isotopes in your simulation setup might be due to the very low primary proton beam energy (13 MeV). When I increased the energy even to 130 MeV, I already started seeing some activation in Water and CH4.
Cheers,
Jerzy
Dear @jemancza,
Thank you kindly for your reply.
In my simulation, what I’m trying to get is the induced radioactivity produced by the neutrons (from13 MeV p+Be) reacting with the methane moderator and the cooling water. When you increase the proton energy from 13 MeV to 130 MeV, the activation in Water and CH4 might be from the high energy proton nuclear reation which penetrate the multi-layered targets and neutrons nuclear reation. So I don’t know if it’s my code that’s wrong or if there’s indeed no radioactive material produced in the neutron field generated by 13MeV p+Be.
Looking forward to hearing your futher reply.
All the best,
Yongguang
Hi Yongguang,
If you know exactly from what reaction you are expecting activation to happen then I suggest you to set up some kind of interaction biasing. I added the following card to your simulation:
which effectively reduces the primary proton inelastic nuclear interaction length in beryllium by a factor of 20.
Please have a look at the description of this card to understand better how it works:
https://flukafiles.web.cern.ch/manual/chapters/description_input/description_options/lam-bias.html#lam-bias
Thanks to that I managed to see some activation in your H2O_pat2 region. I simulated 5 cycles of 250k particles each, but I think you can easily try to go higher than that given the very low primary energy.
Please let me know if you have any doubts.
Cheers,
Jerzy
Hi Jerzy,
Sorry for taking so long to reply to your message. Thank you very much for your patient answers, and I will verify them according to your ideas and solutions in the following days. I will contact you as soon as there is a result.
Thanks again for your reply.
All the best,
Yongguang