Re: [fluka-discuss]: Low neutrons in Poly, Deuterons and artifact?

From: Luigi Salvatore Esposito <>
Date: Fri, 29 May 2015 15:25:30 +0000

Dear Georgios,
FLUKA treats low energy (<20 MeV) neutrons with a multi energy-group approach (please refer to section 10 of the manual).
This implies that low neutron interactions are not simulated as exclusive processes, but by means of a scattering matrix that
describes the probability that a neutron is transferred into a different group after an interaction.
While this approach is normally suitable in most of situation, itís not applicable in an event-by-event analysis in such a thin geometry.

Coming finally to the peaks that you have seen, they represent the energy deposition of a 1-MeV neutron in the kerma approximation.
The peak at 130 keV is due to the kerma factor of a 1 MeV neutron interaction on carbon, while the peak at 76 keV is the one on Neon.
All the best, Luigi

On 26 May 2015, at 18:38, Georgios Tsiledakis <<>> wrote:

Dear experts,

Please have a look at the attached pict/input.
neutrons of 1MeV hits a polyethylene+a very thin front Al plate (~50nm)
and the detector is a 5mm thick gas (Neon).
I would like to have a look at the Energy Deposition inside the gas.
I observe a high peak around 7.3e-5 GeV that doesnt come from protons or e/g.
If I gave a look at the Edep in the poly I also observe a peak around 0.13 MeV.
As far as I know deuteron is not implemented to be transported like other light
ions (4He etc) or not? Do those peaks come from the deuterons?
If yes, what is the right approach in such case?
Shall I use as a simulated spectra the sum of Edep protons + e/g?
The ~50nm Al plate is it ok to be treated as well? or its too thin for fluka estimations?

I am looking forward to hearing from you

thanks a lot in advance

Best regards


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Received on Fri May 29 2015 - 18:50:49 CEST

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