Re: Explanation of the results- FLUKA input file patch

From: Andrea Tsinganis <Andrea.Tsinganis_at_cern.ch>
Date: Wed, 21 Nov 2012 10:43:23 +0100

Dear Dr. Jamil,

If you plot your FLUKA results in log-log scale (or using a logarithmic
scale at least for the neutron energy ) I think you will find that the
proton spectrum you obtain is compatible with the 1H(n,elastic) cross
section in this incident neutron energy range (0.01-20MeV). As previously
mentioned, FLUKA explicitly produces and tracks recoil protons so this
result is the expected one. You are of course missing the contribution from
the Carbon present in the PE since no secondaries are explicitly produced
by FLUKA. Proton production in Carbon via (n,p) reactions, however, starts
at En>13.6MeV, so your spectrum should be reliable at least up to that
energy. You can take a look at the attached modified version of your Excel
file.

As for the GEANT results, it would be interesting to hear from someone with
experience in that code.

Regards,
Andrea

On Wed, Nov 21, 2012 at 6:55 AM, 파르자나아호마드 <mjamil_at_konkuk.ac.kr> wrote:

> Dear Dr. "Stefan Roesler
>
> EMail: sroesler_at_mail.cern.ch
>
>
>
> As mentioned in your previous letter, we have modified the Input
> construction file( Fluka Code), according to your suggestions.
>
>
>
> *When we used the following assumtion as you mentioned to us:*
>
> -> Please note that there is no explicit recoil production on carbon. Thus
>
> -> (after having removed the air) when assigning hydrogen to your target
> you
> -> get exactly 50% neutron and 50% proton produced per primary as it
> should
> -> be. When assigning poly to the target, the neutron fraction goes up
> also
> -> due to the fact that there is no recoil treatment for scattering on
> carbon.
>
>
>
> After modifying we get the attached results, and with this assumption we
> are getting the fast neutron results, similar like the
>
> thermal neutron behavior, (as the results do not match with GEANT4
> results), which looks strange.
>
> Could you please have a look into these new results and the input Fluka
> code., and please guide us, how we can further modify it and get the
> correct results by FLUKA?
>
>
>
> with best wishes,
>
>
>
> Dr. M. Jamil & Kim Hyeon Ki
>
> EMail: mjamil_at_konkuk.ac.kr, go45600_at_konkuk.ac.kr
>
>
>
>
>
>
>
>
>
> ------------ 원본 메일 내용 ------------
> *보낸 사람 :* "Stefan Roesler"<sroesler_at_mail.cern.ch>
> *받는 사람 :* "파르자나아호마드" <mjamil_at_konkuk.ac.kr>
> *참 조 :* fluka-discuss_at_fluka.org
> *메일 제목 :* Re: Explanation of the results- FLUKA input file patch
> *보낸 날짜 :* Fri, 16 Nov 2012 15:48:05 +0100
>
>
> Dear Dr. M. Jami
>
> Before discussing physics there are a two technicalities to clarify:
>
> - your poly is surrounded by a 100m radius *air* sphere. Of course, the
> scoring of secondaries that you refer to is mostly secondaries created in
> this air volume, not in the poly
>
> - your beam is aligned in z while I think you want to have it aligned with
> x (the coordinate in which your target is 0.03cm thick). Just by chance
> you get also interactions in the target since the beam is 2x2cm wide..
>
> Please note that there is no explicit recoil production on carbon. Thus
> (after having removed the air) when assigning hydrogen to your target you
> get exactly 50% neutron and 50% proton produced per primary as it should
> be. When assigning poly to the target, the neutron fraction goes up also
> due to the fact that there is no recoil treatment for scattering on
> carbon.
>
> Cheers
> Stefan
>
>
> On Thu, 15 Nov 2012, ????????! wrote:
>
> >
> > Dear Dr. Stefan Roesler,
> >
> >
> >
> > Thank you for your response to our question.
> >
> >
> >
> > We inserted the neutrons onto the Polyethylene layer, which produced the
> > protons via (n, p) reaction.
> >
> > N + Polyethylene ----> Protons + Recoil fragments
> >
> >
> >
> > We are sending you the sketch out put of the results, this will help you
> to
> > find out how we have evaluated the secondary protons via FLUKA code.
> >
> >
> >
> > Further we are sending you the complete FLUKA code we have used for this
> > study.
> >
> >
> >
> > We hope you will kindly guide us , how to implement the neutron
> transport in
> > FLUKA based on a multigroup
> > approach without explicit generation of secondaries.
> >
> >
> >
> > with best wishes,
> >
> >
> >
> > Dr. M. Jamil &amp! ; Kim Hyeon Ki
> >
> >
> >
> >
> >
> > < BR>>
> >
> >
> >
> >
> > ------------ ?? ?? ?? ------------
> > ?? ?? : "Stefan Roesler"**
> > ?? ?? : "????????" **
> > ? ? : fluka-discuss_at_fluka.org
> > ?? ?? : Re: Some Explanation of FLUKA results is Requested !
> > ?? ?? : Wed, 14 Nov 2012 12:24:47 +0100
> >
> >
> > Dear Dr.Jamil
> >
> > As you may know, neutron transport in FLUKA is based on a
> > multigroup
> > approach without explicit generation of secondaries, except for
> > recoils on
> > hydrogen and protons from 14-N(n,p) reactions.
> >
> > Thus, may I ask you how you have computed the number of
> > secondaries? For
> > an efficient investigation I would also need your input file and
> > any user
> > routines that you use. Please sumit those.
> >
> > Cheers
> > Stefan
> >
> > On Wed, 14 Nov 2012, ???????? 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 d! ifferent peaks with different energies,
> > however for the GEANT 4 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
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >[PutAck.jsp?ack_args=c2VudF9maWxlPW1qYW1pbEBrb25rdWsuYWMua3IvLlNlbnQvMTM1Mj
>
> > g4NDY5M
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> > eHBsYW5
> > >hdGlvbiBvZiBGTFVLQSByZ!
> XN1bHRzIGlzIFJlcXVlc3RlZCAh&to_email=fluka-discuss_at_fl
> > uka.org
> >
> >___________________________________________________________________________
>
> > _______
> > > _____________________________________________]
> > >
> >
> >
> [PutAck.jsp?ack_args=c2VudF9maWxlPW1qYW1pbEBrb25rdWsuYWMua3IvLlNlbnQvMTM1Mj
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> >
> l=sroesler_at_mail.cern.ch____________________________________________________
> >
> ___________________________________________________________________________
> > __]
> >
>
>

Received on Wed Nov 21 2012 - 12:19:47 CET

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