Re: [fluka-discuss]: Clarification on neutron yield

From: Sunil C <csunil11_at_gmail.com>
Date: Thu, 22 May 2014 13:58:11 +0530

Hi

I have seen that the number of emitted neutrons do have a dependence on the
target thickness, particularly if you are using a thickness that is equal
to or more than the range of the projectile. This is one way how you may
"not count" all the neutrons as attenuation/absorption of low energy
neutrons will alter the number.

It may also matter how you are counting them. For example a boundary
crossing estimator will give what emerges from the target, that is net of
production in and absorption by the target. The yield that emerges from an
inelastic interaction can be scored using the Usryiled card. This will
score the neutrons emitted without being attenuated by the target.

Were the conditions similar in both the calculations? Was there a
difference in geometry?

These are just a few thoughts that came to my mind but it is easier to
comment if one can see the input file

Cheers
Sunil


On Thu, May 22, 2014 at 12:11 PM, Benjaminas Marcinkevicius <
b.marcinkevicius_at_gmail.com> wrote:

> Hello everyone,
>
> I have calculated 2 GeV protons impinging on tungsten target and neutron
> yield in FLUKA 56 neutrons per source particle, while in MCNPX 79 neutrons
> per source particle.
> The difference is rather large and I was thinking maybe I do not account
> all the neutrons in FLUKA.
>
> FLUKA defaults were:
> precision
> evaporation with heavy fragments is on
> coalescence is on
> Low-neut transport is on
>
> I took the neutrons from table:
> Number of secondaries generated in inelastic interactions per beam
> particle:
>
>
> However low energy neutrons and neutrons are treated separately and maybe
> this number does not include the neutrons with energy below the 20 MeV ?
>
> As I am quite new to FLUKA any insight on the problem would be helpful.
>
> See attached summary of the FLUKA run.
>
> Thank you for your help in advance.
>
> Sincerely,
> Benjaminas Marcinkevičius
>
>
Received on Thu May 22 2014 - 11:31:19 CEST