RE: [fluka-discuss]: Atmospheric simulations and particle counts

From: Vasilis Vlachoudis <>
Date: Fri, 26 Oct 2018 08:14:15 +0000

Hi Sarah,

It is not clear to me your question. With MGDRAW you are responsible for the counting.
Fluka will call the various ENTRY points when the specific event happens (e.g. boundary crossing, energy deposition, etc....)
For each event with the specific conditions for each step it will be called only once. However a single particle could cross
multiple times a surface but it will be always on a different step and different conditions, position, direction, time etc....

BLACKHOLE I personally try to avoid it since it can alter the results if not carefully used.

it all depends on what you want to count.
I always try to avoid to use the MGDRAW, and prefer the standard scoring USRBDX, USRTRACK,
which you can weight or filter with a user routine (USERWEIGht card). For example you can tell it to ignore the contribution
of the primary particles and record only the secondaries.

From: [] on behalf of Sarah Mechbal []
Sent: Thursday, October 25, 2018 18:52
To: fluka-discuss
Subject: [fluka-discuss]: Atmospheric simulations and particle counts

Dear FLUKA experts,

I had a question about atmospheric cosmic rays shower simulation with FLUKA: is it possible to have a particle counted twice in the MGDRAW routine?

Let me describe our setup:
We inject an isotropic flux of protons following a power-lay at the top of the atmosphere, which is described with 291 spherically concentric layers, going from 0 to 998

We record with the MGDRAW routine boundary crossings at layers of our choosing. For events with a high zenith angle, the particle will traverse the layer multiple times, upward or downward, sometimes interacting in the process: could a particle ever be miscounted twice in the MGDRAW routine? Would it be better to assign a BLACKHOLE material below the layer of interest to avoid such problem? We are also interested in knowing the contribution of secondary particles at different atmospheric depths.

Thank you for the help you provide,

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Received on Fri Oct 26 2018 - 11:20:55 CEST

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