Re: [fluka-discuss]: Probelm regarding the neutron fluency and moderation of neutrons in graphite

From: Anna Ferrari <>
Date: Mon, 03 Jul 2017 17:35:04 +0200

Dear Tom Janzen,

yes, it is always a good practice to send the input file when you need
Please do it... I have the suspect that you simply did not call the right
low-energy neutron cross section for your material graphite. Once you have
defined the material (for example with the name GRAPHITE), you should have a
line like:
LOW-MAT   GRAPHITE   6.       -3.       296.      0.0      
      0.        CARBON
to link the material to the cross section of graphite bound natural Carbon.
Did you use the LOW-MAT card?

Hope it helps,

...moreover, be careful: the radiometric quantity is Fluence, not Fluency
(automatic corrector does not work well in this case!)

Am Mon, 3 Jul 2017 16:11:39 +0200 schrieb "Tom Jonas Janzen"
> Hello fellow FLUKA Users and FLUKA Experts!
> I have finally simulated all meterials that i needed (PMMA, HDPE, Water and
> Graphite) for my master thesis and have all the results. Everything looks
> fine except the plot of graphite.
> The Maximum oft he neutron fluency is shown at the energy point of 2E-11 GeV
> for the materials PMMA, HDPE and Water. This results shows me, that the
> increase of the Neutron fluency is due to the moderation of neutrons.
> Only the results of graphite and the plot of graphite shows me some strange
> results which i can't put together. Shouldn't be the plot of graphite be
> similiar as the plots oft he other ones?
> Does the FLUKA community have any ideas, why the results of graphite are so
> different? What could be the reason? My only idea or conclusion was, that
> there could be an alternative cross section for carbon in graphite bound for
> a different energy spectrum.
> Ifm y INPUT file is needed for solving this problem, then i can send it
> also.
> Thank you all for your help in advance!
> Best regards,
> Tom Janzen
Dr. Anna Ferrari
Institute of Radiation Physics
Helmholtz-Zentrum Dresden-Rossendorf e.V.
Tel. +49 351 260 2872

Vorstand: Prof. Dr. Dr. h. c. Roland Sauerbrey, Prof. Dr. Dr. h. c. Peter
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Received on Mon Jul 03 2017 - 20:02:27 CEST

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