I am a beginner in FLUKA and have a question regarding the nuclear cross sections that are being used. I am irradiating a B11 target with protons and am interested in the (p,a) reaction. I understood that FLUKA makes use of the EXFOR database for the cross sections, which for this reaction peak at around 600-700 keV incident proton energy. I see that the EXFOR data is (nearly) not tabulated for higher incident proton energies (~10-100 MeV) and was wondering if you could tell me what cross sections are used by FLUKA in that energy range.
Not at all.
(Not sure where you took this misleading information).
First of all, FLUKA calculates the proton reaction cross section (sigma_R) according to its own parametrization. Its value - at the input beam proton energy - is given in the material table of the standard output file in the form of inelastic scattering length (lambda [cm] = molar mass [g/mol] / (rho sigma_R N_A), where rho [g/cm3] is the material density and N_A [1/mol] is the Avogadro constant).
Then, the probability of a specific reaction channel, such as (p,a), is determined by the FLUKA reaction model, yielding the proton reaction final state at any energy.
Thank you for the quick reply. The information comes from another post on the forum (Model in FLUKA for p-B fusion). It says that the parametrization expression was fitted directly to EXFOR data. This is incorrect then?
Dear Atia,
no, that post is fully correct, since it reads: The integrated cross section for protons on target nuclei in FLUKA is implemented as a general effective parametrized expression fitted to experimental nuclear reaction data. For p on 11B at the particularly low energies you care about, it was directly fitted on EXFOR data.
This means that the reaction cross section parametrization was adjusted to EXFOR data in that specific corner, but its general expression - covering the whole energy and material range - does not imply the use of data points. As indicated above, you can (indirectly) retrieve its value at the selected energy in the standard output file (*001.out).
Moreover, the above refers to the reaction cross section that includes all available channels. The cross section of a given channel results from the reaction model (and not from EXFOR data, which are rather used for benchmarking).