Re: [fluka-discuss]: Understanding the difference between USRBDX and USRTRACK card

From: wurth <wurth_at_ipno.in2p3.fr>
Date: Mon, 13 Jul 2015 22:41:22 +0200

Hello Ana,

It seems that there is some 2 pi factor of difference between the peaks
of your USRTRACK/USRBDXs distributions.

If it is the case, that is probably because if you used usxsuw program
to compute your USRBDX results, you do not have to multiply (again) by 2
pi, the program already took care of that.

Please see this rather old but very useful discussion (especially the
fluence lecture by Alberto Fasso and Alfredo Ferrari which follows in
thread) :
http://www.fluka.org/web_archive/earchive/new-fluka-discuss/0535.html

Best regards.
Sebastien.


Le 2015-07-13 16:20, Ferreira De Almeida Lourenco, Ana wrote:
> Dear Fluka experts,
>
> I simulated a proton beam in a target cylinder and I am scoring
> fluence in a ring detector that surrounds my target using a USRBDX and
> a USRTRACK card.
>
> Results from USRBDX card are integrated over solid angle and were
> normalized to the area of the detector and multiplied by the energy
> bin width and by 2pi (one-way scoring) in order to get fluence in
> units of cm-2.
>
> Results from USRTRACK card were normalized to the volume and
> multiplied by the energy width in order to get fluence in units of
> cm-2.
>
> I understand that USRBDX is a boundary crossing fluence (or current)
> estimator, and USRTRACK is a track-length estimator but I am
> struggling to understand the differences between these two cards when
> looking at my results.
>
> The graph below shows Fluence (cm-2/primary) differential in energy
> using a USRBDX card (outer boundary: from RING to AIR, inner boundary:
> from AIR2 to RING), and using a USRTRACK card.
>
> Why is the fluence from USRBDX higher than the fluence from USRTRACK
> card? I am aware that in some Monte Carlo codes the way how fluence is
> estimated is just valid to convex volumes/surfaces. Is this the case
> for FLUKA? In my geometry I am scoring fluence in a concave
> surface/volume.
>
> Please find in attachment my input file.
>
> Many thanks,
>
> Ana

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Received on Tue Jul 14 2015 - 00:02:24 CEST

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