Proton transport problem using MCNP

[Antonio_A]

Hello everyone !

I wanted to ask you if anyone ever encountered problems with proton transport using MCNP. In particular, the production of electrons when protons interact with matter. I have been trying to figure it out modifying the different physics cards (phys, lca, ...) with no result. Since a proton is a charged particle, ionization is expected and not even a single secondary particle is created while, in the output file most (if not all) of the incident protons are lost by energy cutoff meaning that they lose energy.
If anyone with experience in proton transport could enlighten me or give me some clues, it would be great.

Thanks,
Antonio

 

[Greg Bernhardt]

Thanks for the thread! What version of MCNP is one using, MCNPX or MCNP6?

 

[Astronuc]

From - https://mcnp.lanl.gov/pdf_files/la-ur-13-22934.pdf
it states, "Transport with elastic and inelastic nuclear scattering, Continuous slowing down approximation, energy and angle straggling, magnetic field effects"

There may be some insight in this thesis - Using MCNPX to Calculate Primary and Secondary Dose in Proton Therapy
https://smartech.gatech.edu/bitstream/handle/1853/39499/ryckman_jeffrey_m_201105_mast.pdf

One could search on "MCNP proton slowing down" or "continuous slowing down approximation" with or without MCNP

I have a colleague who has used MCNPX and MCNP6 to simulate the effects of proton beam on targets.

 

[Antonio_A]

Thanks for your replies

What version of MCNP is one using, MCNPX or MCNP6?

MCNP 6

There may be some insight in this thesis

I already have looked into it, it describes well how to setup the physics transport of protons in the input file but it treats a completely different case and it is useless in my situation as i described the most complete case for protons.I have found PIXE (particle-induced x-ray emission) cross-section libraries. This is not a PIXE problem but since it treats the ionization as main process and it is also what i am interested in, i taught that i might as well have a look at it. Now, i don't know how to make these libraries work with mcnp and if anyone (you know) has already tried this, i would love to know how you did it.

Thanks,
Antonio

 

[Antonio_A]

I finally have an answer. For those wondering, MCNP6.1 is not able to compute this kind of cases. Delta-ray production from charged particles is implemented in MCNP6.2 which will be available by the end of this month.

Topic can be closed.

 

[evjanuclear]

Hi, I have a similar problem.I'm simulating in MCNP6 the reaction of proton beam on targets but in the simulation the 96% of the proton are lost for energy cutoff.
I don't understand why happen that. I use a tally4 to obtain the reaction in the target, but I suppose the results are wrong because the lost of protons (if they are lost they can´t interact isn´t it?)

Any idea?

Thanks,
Eva