Electro-nuclear interactions in FLUKA

Hello FLUKA experts,
after some days of deep diving into FLUKA via the beginner and advanced tutorial, I have another question.
I am currently at the state, where I roughly understand the FLUKA workflow. But only roughly…and I am wondering if what I am trying to do is generally even possible.
I will try to outline what my initial plan was and hope anyone can put it into context for me and tell me if FLUKA is able to do it.

In the scope of my master thesis I am looking at an electron beam imping on a tungsten target. This simple setup serves to study electro-nuclear interactions. These interactions are background events for the experiment I am working on and thus are very important to understand. For example neutrons from electro-nuclear interactions are one big neutral hadronic background that we want to study.
But also other neutral hadrons (e.g. Klongs) are of interest for my study.
To do so I have already implemented this simple setup in Geant4 and studied the neutral hadronic backgrounds there. But we have found out that Geant4 does not simulate these events with a super high accuracy and we also have already found instances where Geant4 does weird stuff.

My question is thus: is FLUKA able to simulate electro-nuclear interactions with huge energy transfers of the beam electron to the nucleus? In the cases we look at the 3.2 GeV beam electron has only 75 MeV left after the electro-nuclear interaction.
I did see that electro-nuclear interactions have been added since FLUKA 4.0, but I am not sure it encompasses what I want to look at.
If such electro-nuclear interactions are possible to simulate with FLUKA then I would be really happy to get any sort of documentation on the model used to simulate such events.

Thanks in advance to anyone taking the time to help!
Kind regards,
Laney

Hi Laney,
extreme energy transfer are indeed included in the FLUKA treatment of electro-nuclear reactions, as the following spectrum of secondary electrons resulting from electro-nuclear reactions at 3.2 GeV on natural tungsten shows:


Note that, depending on your target thickness, reactions at lower electron energies and especially reactions by bremsstrahlung photons may play a role.
We miss an exhaustive description of the implemented model, but you can find some hints at https://doi.org/10.1051/epjconf/201714612005 (Section 3) where the two components of the virtual photon spectrum are briefly introduced.

Hello Francesco!
Thank you for your reply this has helped a lot.
I have a question regarding your reply, as you hinted at the impact of bremsstrahlung photons.
In Geant4 I am able to create my own physics list, to only include electro-nuclear processes and no basic electromagnetic interactions such as Bremsstrahlung. Is this or something similar also possible with FLUKA (I found the PHYSICS card, but am not sure it can cut off the Bremsstrahlung processes).

Thanks again for your reply,
Kind regards
Laney

You can DISCARD photons (still taking into account the electron energy loss due to bremsstrahlung!).

Thanks for your reply, sadly also photons are part of the background I am investigating, so completely disregarding them is not possible. Maybe enhancing the electro-nuclear processes via LAM-BIAS will do the trick.
Kind regards
Laney

You wrote above about not including bremsstrahlung, which is a choice vastly killing the photon population.
A high photon cut in EMFCUT will prevent bremsstrahlung photon generation, while photons from electro-nuclear reactions will be generated anyway, but not transported further.
The biasing asymmetry you consider (LAM-BIAS only for ELECTRON, and not PHOTON) will impact the likelihood of the reaction type in the simulation, attributing at the same time a lower statistical weight to the electro-nuclear products.
If you plan an event-by-event analysis, as your other thread suggests, you will be naturally able to filter the reaction products as a function of the projectile.

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