Re: Some Explanation of FLUKA results is Requested !

Dear Dr. Jamil,

I have no experience with GEANT, but concerning the FLUKA result I think
that what you see is the recoil proton spectrum from polyethylene which
FLUKA explicitly produces for hydrogen. I would guess that the structure
you observe at higher energies - especially since the H(n,el) cross section
is smooth - is an artefact due to the fact that you are using neutrons
<20MeV crossing a thin target (0.3mm): when there is a reasonable
probability that a neutron will not interact more than once, then the
multigroup approach implemented in FLUKA becomes less reliable.

A look at chapter 10 of the FLUKA manual to understand the treatment of
neutrons <20MeV in FLUKA (particularly section 10.1.1) should clarify these
points. There should also be other similar past threads in the FLUKA list.

Perhaps the experts can provide some greater insight...

Cheers,
Andrea

On Wed, Nov 14, 2012 at 10:18 AM, 파르자나아호마드 <mjamil_at_konkuk.ac.kr> wrote:

> Nov 14th , 2012
>
>
>
> Dear Fluka Users,
>
> "fluka-discuss" fluka-discuss_at_fluka.org
>
>
>
> As the general User of the Fluka MC code, we are sending you this mail.***
> ***
>
> We hope that some one will kindly respond to our question.****
>
> For the detection of fast neutron, we inserted a fast neutrons in the
> energy range of En = 20 MeV onto the Polyethylene ?convertor and evaluated
> the response via FLUKA and GEANT 4 MC codes. ( The Results are attached
> as EXECL File).****
>
> The results are taken via GEANT4 and FLUKA separately, however If you
> have a look into the results , these show a large discrepancies as obtained
> by the FLUKA.****
>
> It shows the 4 different peaks with different energies, however for the
> GEANT4 case the response increases smoothly.****
>
> The data was taken 2-3 times repeatedly in order to re-confirm it.
>
> ****
>
> **We hope that soem one can explain us about the FLUKA graphs.**
>
> ** **
>
> Waiting for your reply,****
>
> ** ***Dr. M. Jamil & Kim Hyeon Ki*
>
> *Konkuk University, *
>
> *Seoul 143-701, KOREA*
>
> *EMail: mjamil_at_konkuk.ac.kr, go45600_at_konkuk.ac.kr*
>
> **
>
> **
>
> ** **
>
> ** **
>
>
>
Received on Wed Nov 14 2012 - 14:54:40 CET