Re: x-Rays Transport

From: Alberto Fasso' <>
Date: Sun, 5 Jul 2009 10:32:56 -0700 (PDT)

Dear Ali,

First of all (and this applies not only to you, but to all users
writing to this list) it is useless to ask questions about a FLUKA
problem without sending also at least the input file. Without the
input file, we can only guess, and the possible causes are thousands.

But perhaps in this case you are luckier, and my guess can be successful.
100 keV are lower than the transport and production thresholds set by
most defaults. You should set both thresholds lower yourself using
command EMFCUT, once with SDUM = PROD-CUT (for production) and once
with SDUM blank, for transport. Read carefully the manual about that
command (please notice that transport thresholds are set by region, and
production thresholds are set by material).

Another important thing: the thresholds you are using are reported in
the .out file. Check that they are how you want them.

Productions thresholds are reported as follows:

1 Quantities/Biasing associated with each media:

       Rho = 2.35000 g/cm**3 Rlc= 9.84627 cm
       Ae = 1.51100 MeV Ue = 5766.71 MeV
       Ap = 0.333333 MeV Up = 5766.20 MeV
  (Ae = production threshold for electrons, expressed as _total_ energy, i.e.
   kinetic plus mass. In this example, 0.001 GeV kinetic.
   Ap = production threshold for photons)

Transport thresholds are reported as follows:

1 Correspondence of regions and EMF-FLUKA material numbers and names:
        Region EMF FLUKA
           3 2 CONCRETE 28 CONCRETE
      Ecut = 1.5110E+00 MeV, Pcut = 3.3333E-01 MeV, BIAS = F, Ray. = F, S(q,Z) = T, Pz(q,Z) = F
  (Ecut = transport transport threshold for electrons, expressed as _total_
   Pcut = transport transport threshold for photons)

Kind regards,


On Sun, 5 Jul 2009, Ali Koosha wrote:

> Dear Fluka experts
> I want to perform a simulation of x-rays (~100 keV) beam incident on a
> simple Cu thin/thick target;
> but my attempts failed to attain a non-zero output from the code, under the
> following conditions:
> source = a monodirectional "PHOTON" annular beam having nominal energy of
> ~100keV
> geometry = a simple rcc
> score = surface and track estimate of "PHOTON"s flux
> misc = turn EMF. It seems that x-rays don't transport
> at all.

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 Sun Jul 05 2009 - 20:42:53 CEST

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