Re: [fluka-discuss]: Thermal peak in neutron spectrum

From: Talanov Vadim <>
Date: Fri, 1 Apr 2016 08:52:00 +0200

Dear Felix,

Without looking at your geometry but seeing that you mention "moderator"
I would guess that what you get at this 80 meV peak is actually the
"effective" moderator temperature, and if this guess is correct then
maybe a useful starting point for further understanding would be Chapter
13 from the Handbook of Spallation Research by Filges and Goldenbaum,


On 31.03.2016 11:44, Felix wrote:
> Dear FLUKA experts,
> I scored photoneutron spectra at several positions within a electron
> linac bunker and plotted them as normalized fluence per unit lethargy
> (see attachment). Position 1 lies directly beneath the source, position
> 2 some meters away and position 3 within a maze.
> At about 80 meV a peak arises and i thought that it should correspond to
> the thermalized neutron energy (k*T), but wouldn't that indicate a
> moderator temperatur of about 650 degrees Celsius?
> I did not change any LOW-MAT properties in my input file, so i thought
> FLUKA would use the neutron cross section sets corresponding to room
> temperature (296 K), which should give a peak at about 25 meV instead.
> Are you able to understand this effect and are there any mistakes in my
> argumentation?
> Thank you in advance
> Best Regards
> Felix

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Received on Fri Apr 01 2016 - 16:48:49 CEST

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