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

From: Georgios Tsiledakis <Georgios.Tsiledakis_at_cern.ch>
Date: Sat, 30 May 2015 08:18:29 +0000

Dear Luigi,

Thank you very much for your answer.
In my study I am interested in counting efficiencies (total number of counts in the gas volume).
Since the 50nm thickness of Al foil window produces artifacts, how I could modify my input using specific
cards in order to be able to simulate correctly?
What is the minimum thickness of Al that I could consider that FLUKA can be suitable?
If the Al foil has a thickness of 1-10 microns (instead of 50 nm) do you think my approach as it is described in my input file might work?

Thank you very much in advance

Best regards

Georgios

________________________________
From: Luigi Salvatore Esposito
Sent: 29 May 2015 17:25
To: Georgios Tsiledakis
Cc: fluka-discuss_at_fluka.org
Subject: Re: [fluka-discuss]: Low neutrons in Poly, Deuterons and artifact?

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 <Georgios.Tsiledakis_at_cern.ch<mailto:Georgios.Tsiledakis_at_cern.ch>> 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

Georgios
<FlukaDiscList.png><5mmNe-Al50nm.inp>



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Received on Sat May 30 2015 - 12:01:05 CEST

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