Units of DETECT CARD and WHAT Nuclear DATA file Used?

Dear FLUKA Experts,

A few months ago, I posted this question (DETECT Card - Spikes in the Spectrum - #4 by dcalzola) about stimulating energy deposition events in low-pressure gasses using the DETECT card, which was succinctly answered to my satisfaction

But lately, I’ve been working with MCNP 6.2 to reproduce this same simulation and I got stuck on which nuclear crosssection data to use. ENDF, JENDL or what?

Question 1:
So what nuclear data files (including the version) are used in FLUKA and how can I check this information in FLAIR?

Question 2:
I also understand that a single primary particle can undergo many collisions within the target region, depositing a different energy value per collision (belonging to different energy bins) of my detector.

So according to this image, what does dN/dE [1/GeV] mean? Is there any normalization to the NPS (number of particles simulated)?

Question 3:
Does anyone know the counterpart (f-tally) of DETECT in MCNP? I’m using the “F8” tally together with “E8”, which records pulses per NPS (i.e., energy deposition events in the assigned energy bins).

I’ll be grateful for any suggestions.



Hello Zavier,

  1. FLUKA does not use a nuclear data library for protons. Dedicated models are used in FLUKA to model their behaviour with target nuclei. For neutrons, you can select your favorite one from here:
    FLUKA libraries for low-energy neutron pointwise interaction cross sections | The official CERN FLUKA website

  2. Correct. The plot represents the distribution of energy deposited per event in the region(s) making up the detector. By “event”, I mean energy deposited in the detector region by one primary particle and its descendants. As usually, the results are given per primary particle.

  3. To my knowledge, you should get similar results. In both cases, (FLUKA and MCNP) you shall not use biasing when scoring these energy distributions (Variance Reduction for Pulse-Height Scoring).

Since you are dealing with relatively low-energy protons, I do not expect huge differences among codes. Let me know in case of trouble!

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