RE: photoneutron

From: Joachim Vollaire <>
Date: Thu, 10 Feb 2011 18:13:38 +0000

Here is a few hints which I hope will help you.

>> 1) I read low neuron transport in fluka manual and fluka course and I found that
>> FLUKA set the first material in table In the presentation
>> file of fluka course, setting of LOW-MAT card is not clear about compound while I
>> inserted 6 compounds such as concrete, air, kapton, etc. With considering CARBON in
>> air and concrete as examples and CARBON types are different in both
>> (Gas in AIR and Graphite in Concrete) I want to know that is transport of
>> low neutron applied via setting NEW-DEFA in compound material or not?

If you use the NEW-DEFAU, transport of neutron down to thermal energies is included.
The LOW-MAT card is used to set the correspondence between FLUKA material and cross sections.
You can find below the example from the manual for the common case where different
CARBON types are needed (as in your problem)

     Example (number based):

  MATERIAL 6. 12.011 2.000 6. 0.0 0. CARBON
  MATERIAL 6. 12.011 1.700 15. 0.0 0. GRAPHITE
  MATERIAL 6. 12.011 3.520 16. 0.0 0. DIAMOND
  LOW-MAT 15.0 6. -3. 296. 0.0 0. CARBON
  LOW-MAT 16.0 6. -2. 296. 0.0 0. CARBON

  * We have three materials with the same atomic composition, but different
  * density (amorphous carbon, graphite and diamond). Graphite is declared as
  * having the cross section of Graphite bound natural Carbon, while diamond
  * is declared as having the same low-energy neutron cross section as Free Gas
  * Carbon.

>> 2) I set electron beam with following features:
>> BEAM -.0188 -.1 -0.0 -1.18 -1.18 1.0ELECTRON
>> BEAMPOS 0.0 0.0 0.001 NEGATIVE
>> Unfortunately I don't have clear output data in SSD100 that you can see
>> it in attachment and I think it is related to beam. I don't know how can
>> I reach to data in this point because fast neutron and a little thermal neutron is been seen
>> in experimental data in SSD100.

The beam definition seems reasonable. I am not sure I understand clearly your question otherwise.
You are activating PHOTONUC reactions and biasing the corresponding cross sections with is good
for this type of calculations. If you are not satisfied with the statistics of your output spectra you may
consider divided you geometry in regions and use region based biasing...

Hoping this is helpful for you
Best regards
Joachim Vollaire
Received on Fri Feb 11 2011 - 10:26:10 CET

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