Hi Ricardo,
Never mind, I've realized that these are what should be obtained when
multiplying the fluence by the energy bin width. The DX*Y value option on
Flair should achieve the same results too. Thanks.
Best regards,
Sizwe
On Wed, May 27, 2020 at 1:21 AM Ricardo Manuel Dos Santos Augusto <
r.s.augusto_at_cern.ch> wrote:
> Dear Sizwe,
>
> With the following scoring cards (from det1 -> target, target -> det2):
>
>
> *...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....
> USRBDX 99. NEUTRON -21. det1 TARGET
> nflux-i
> USRBDX 1E-14 1. &
>
> USRBDX 99. NEUTRON -21. TARGET det2
> nflux-f
> USRBDX 1E-14 1. &
>
>
> indeed one gets 0.99 and 1.03 (Neutron/primary) for nflux-i and f,
> respectively. The overall increase in neutron fluence is expectable since
> you are shooting a monoenergetic beam of fast neutrons into polyethylene,
> resulting into various secondaries being generated (including neutrons).
> Some of the secondary neutrons will add up to the neutrons exiting the
> target, hence your fluence increment.
>
> However, note that you do get a reduction of the neutron fluence at 14 MeV
> as the primary neutrons traverse the target. As you add up more layers to
> your setup the amount of higher energy neutrons will be further reduced in
> favor of lower energy neutrons. The degree of variation will depend on the
> material properties and geometry of the layers.
>
> Hope this helps,
> Ricardo
>
>
> //Ricardo dos Santos Augusto
> TRIUMF-EH&S
> Office: +1 604 222 10 47 (6375)
> 4004 Wesbrook Mall,
> Vancouver, BC V6T 2A3, Canada//
> ________________________________________
> De : owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] de
> la part de SIZWE SCELO MHLONGO [3698012_at_myuwc.ac.za]
> Envoyé : mardi 26 mai 2020 18:56
> À : fluka-discuss_at_fluka.org
> Objet : [fluka-discuss]: Scoring primaries
>
> Dear fluka experts and community,
>
> I am doing calculations with the aim to find a suitable neutron moderator
> material thickness. In my input (attached) I have a beam of 14 MeV neutrons
> going through a polyethylene cylinder (h = 2 cm, r = 8.5 cm). I made two
> scoring regions - one is for scoring beam particles before the beam
> interacts with the target and the other is for scoring the beam particles
> after going through the target region (I chose usrbdx as estimator). I
> noticed that, although I requested 100 000 histories in my runs, the
> fluence scored before the beam interacts with the target is less than the
> requested primaries;
>
> Furthermore, the moderated spectrum (when polyethylene and water are used)
> tends to have a high fluence of thermal neutrons - even higher than the
> requested primaries. What could be the cause of this? Thanks.
>
> Best regards,
>
> Sizwe
>
>
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>
>
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Received on Fri May 29 2020 - 22:46:53 CEST