[fluka-discuss]: Thermal peak in neutron spectrum

From: Felix <felix.ernst.horst_at_lse.thm.de>
Date: Thu, 31 Mar 2016 11:44:30 +0200

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

Thank you in advance

Best Regards


Felix Horst, M.Sc.
Institut für Medizinische Physik und Strahlenschutz (IMPS)
Technische Hochschule Mittelhessen
Wiesenstr. 14, 35390 Gießen
Raum D10.12a
Telefon: 0641 309 2642

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(image/png attachment: neutron_spectra_lethargy.png)

Received on Thu Mar 31 2016 - 13:30:24 CEST

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