Re: [fluka-discuss]: Photon and Electron pulse-height tallies (FLUKA's DETECT vs. MCNPX's F8)

From: Jean-Emmanuel Groetz <>
Date: Mon, 03 Oct 2016 10:25:35 +0200

Dear Nima,

Not so easy to fix your problem.
May be the first thing to do is to compare for both codes the fluence
of your incident particles in your scintillator, i.e. with the F4 tally
Another thing for MCNPX is to activate the mode e,p (electrons &
photons) and also the ITS code (through the DBCN card).
Check also the cut-off energy for both particles. It seems to me that
in the case of PRECISIO in FLUKA, you must lower the cut-off to 1 keV
(by default in MCNPX), since the threshold is set at 100 keV.

One remark: I don't understand why you didn't use a simplest form the
binning energy in MCNPX.

Jean-Emmanuel Groetz
Laboratoire Chrono-Environnement UMR CNRS 6249
Université de Franche-Comté
16 route de Gray
25030 Besançon Cedex

mailto :
tel : +33 (0) 3 81 66 65 07
fax : +33 (0) 3 81 66 65 22

Le dimanche 02 octobre 2016 à 22:57 +0330, Nima Ghal-Eh a écrit :
> Dear FLUKA experts,
> I have a question regarding the comparison between pulse-height
> tallies 
> of FLUKA and MCNPX codes.
> I have considered a beam of 1MeV photons incident on a plastic 
> scintillator and then I replaced the photons with electrons of same 
> energy. Using both FLUKA and MCNPX, I obtained the pulse-height
> tallies, 
> i.e., DETECT card and MCNPX' F8 tally.
> In case of photon beam, as seen in Page 1 of attached file, when
> FLUKA's 
> so-called dN/dE values are multiplied by 20, the two distributions 
> become comparable, however some dependencies exist in low-energy
> region 
> (the energy binning in MCNPX input has been set as the one in
> FLUKA's 
> DETECT card to avoid any difference associated with energy binning:
> this 
> is why the attached file has too many pages!).
> The difference between FLUKA's DETECT and MCNPX' F8 tally is 
> considerably large in case of electron beam as seen in Page 24 of 
> attached file. All FLUKA's dN/dE values have been multiplied by 10
> to 
> set two distributions equal at 1.0MeV.
> My questions are in following:
> (1) Why do these two codes exhibit large differences in electron 
> pulse-height tallies?
> (2) What are the precise conversion factors between the pulse-height 
> distributions generated with FLUKA and MCNPX codes.
> Thank you very much in advance and looking forward to hearing from
> you 
> soon,
> Best regards,
> Nima Ghal-Eh.

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Received on Mon Oct 03 2016 - 12:02:05 CEST

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