Energy deposition with high photon thresholds

Thank you for your reply, Sir.
Following your corrections and trying to implement a high production and transport tresholds for photons (as seggested here Reason for the shift in the maximum of the energy deposition). I imposed the following tresholds:

Nevertheless, I am still having photons production (USRBIN plot) as in the case with default tresholds.

I am trying to not have photons in order to see the effect on the energy deposition curve.


Hello Lovepreet,

We’d be happy to take a further look.

Could you please upload the exact .flair or .inp file with which you witness this effect? Also any user routine you might be using.

In the meantime, please note that cutting out photons was not a recommendation, simply a way to assess that their effect on your previous near-surface problem was negligible.

We stay tuned,


Dear Francesc,

Thank you for your reply and help. Now, I am trying to understand the difference between the energy deposition in the W and C far from the surface, so I was inquiring about the photons.

Please find attached the required files.
Carbon_Scan1.flair (3.4 KB)
Carbon_Scan8.flair (3.7 KB)
WPTE_W.f (11.3 KB)


Hello Lovepreet,

I took the liberty of updating your Carbon_Scan8.flair, to make sure that the runs with low and high thresholds are cleanly separated. I just put your EMFCUT cards under a preprocessor directive with the label hithr and then add two runs: one leaving default thresholds, and one with high photon thresholds.

If you issue both runs, process, and plot one by one all additional plots in the Plot tab, you’ll eventually end up with the following plot:


…which is indeed what you’d expect: for high photon thresholds: no signature of photons tracks.

Could it have been a file bookkeeping hiccup?

Hope this helps,


PS: looks like your plot above (factor ~2 lower than the one here) is for some intermediate photon threshold value.

I got my answer, thanks!
Just a curiosity. In the post before you wrote “For your question (~7 MeV e-) we can focus on a purely electromagnetic problem (e- and photon transport).” I was wondering where I can get this information about what processes to consider. Please forgive my lack of knowledge in this field, I am trying to understand the physics behind the plots.


Hi Lovepreet,

we can focus on a purely electromagnetic problem

Indeed, my comment above was triggered / in relation to this sentence in your original question:

(maybe related to the dependence of the cross sections on the energy of the particles, the reactions that take place, etc.)?

to indicate that nuclear reactions were not relevant in your problem.

Regarding electron interactions, in the reply to the aforementioned post I tried to elaborate how the basic interaction mechanisms at play manifest themselves in your problem.

For additional information, and to also have a first introduction to the relevant interaction mechanisms for photons, you may want to have a look at this (very gentle) overview presented in the last FLUKA Beginner Online training (click on the various days and the respective “clip” icons to access all material session by session).

Cheers to a nice weekend,


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