Re: question about AUXSCORE card + dose

From: Alberto Fasso' <>
Date: Thu, 9 Jul 2009 18:00:30 -0700 (PDT)

Probably you will judge me pedantic, but I would like to add a
What Andrea said is exact, concerning the way the dose is technically scored
by FLUKA. But be careful: what happens in the real physical world is
In the real world photons don't ever deposit ANY dose: they are indirectly
ionizing and the ionization is all done by electrons and positrons
liberated or produced by photons.
In FLUKA, energy is "deposited by photons" when the photon energy becomes
lower than the photon transport threshold: that energy is then deposited on
the spot. See value of Pcut on your *.out file (search for the string
   "Correspondence of regions and EMF-FLUKA material numbers and names").
You can change that threshold using command EMFCUT
Probably there are also a few other rare cases, for example when
fluorescence/Auger has not been requested and the corresponding energy
is deposited on the spot.
In any case, it must be clear that the amount of "photon dose" is strictly
related to user choices: if you change the cutoff energy, you get a
different result. And the "photon dose", being only the energy of photons
below threshold, is obviously always smaller than the "electron dose".

And, despite the popular success among the users of the possibility to
filter dose deposition with AUXSCORE, getting "neutron dose", "proton
dose", etc., it must be remembered that nearly ALL dose is electron
dose. "Proton dose" is energy transferred by protons to electrons with
energies lower than the delta-ray threshold (again, dependent on a user
choice). "Neutron dose" in FLUKA is kerma, which in the real world would
be ionizing charged recoils, and they too would ionize by transferring
energy to electrons.
The only exception of NIEL=Non Ionizing Energy Loss, which will
be introduced soon into FLUKA, and which refers to kinetic energy
transferred to nuclei without ionization. But I am not sure that it
must be considered part of the dose, and anyway it is always many orders
of magnitude smaller than dose from ionization.

So, to summarize: if FLUKA allows you to calculate dose not due to
electrons, it is only a technical artifact, with results depending
on your threshold settings (transport thresholds or delta-ray production
thresholds). In the real world there is only electron dose.


On Thu, 9 Jul 2009, wrote:

> Dear user,
> about
> "If I want to measure the DOSE deposited by only photon and only
> electron how can I measure it with USRBIN card ?"
> See the information written in the manual for the AUXSCORE card:
> Examples:
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
> USRBIN 10.0 208.0 -50.0 10.0 10.0 10.0Ene.p
> USRBIN -10.0 -10.0 -10.0 100.0 100.0 100.0&
> AUXSCORE 2.0 1.0 1.0
> * The above AUXSCORE card will filter the energy scoring of the
> * USRBIN card to only the energy that is deposited by protons
> In your input you've used:
> USRBIN 10.0 228.0 -86.0 35.0 35.0
> 133.0ElectronB
> USRBIN -35.0 -35.0 98.0 70.0 70.0 70.0 &
> USRBIN 10.0 240.0 -87.0 35.0 35.0
> 133.0ElectronB
> USRBIN -35.0 -35.0 98.0 70.0 70.0 70.0 &
> AUXSCORE 2.00 3.0 6.0 7.0 AMB74
> I think that you've to change the:
> AUXSCORE 2.00 3.0 6.0 7.0 AMB74
> in:
> AUXSCORE 2.00 3.0 6.0 AUXSCORE
> 2.00 3.0 7.0 AMB74
> In this way, you've the dose due to electrons in ***fort.86 and the
> equivalent dose due to elctrons in ***fort.87.
> Ciao
> Andrea

Alberto Fasso`
SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025
Phone: (1 650) 926 4762   Fax: (1 650) 926 3569
Received on Fri Jul 10 2009 - 10:37:19 CEST

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