[fluka-discuss]: Re: FW: USRBDX part/pr error?

From: Stefan Roesler <sroesler_at_mail.cern.ch>
Date: Tue, 17 Dec 2013 10:57:50 +0100

Dear Hakan

It seem to be a rounding artifact: you have not defined explicitly an
upper scoring limit in USRBDX (What(1) in the continuation card). Thus,
FLUKA uses the beam energy. At the same time, you request scoring of
BEAMPART that by definition has exactly the energy as that of the scoring
limit...

I suggest that you define a maximum energy for scoring explicitly in
USRBDX that is slightly higher than the beam energy. It seems to give the
expected results in the few tests that I did.

Cheers
Stefan


On Tue, 17 Dec 2013, Joachim Vollaire wrote:

>
>
> -----Original Message-----
> From: owner-fluka-discuss_at_mi.infn.it [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of hakan akyildirim
> Sent: 03 December 2013 12:38
> To: fluka-discuss_at_fluka.org
> Subject: [fluka-discuss]: USRBDX part/pr error?
>
> Dear FLUKA users;
>
> Recently, I have been studying on the PHOTONUCLEAR absorption cross sections of Carbon-12 and Oxygen-16 at 10-30 MeV photon range. I have realizad that, for some energy values, my USRBDX estimator (one way current) gives 0.0000 part/pr But when I increase or decrease the energy in a very small amount, the result differs from 0.0. For example,
>
> E_gamma=13.0E-2 => part/pr=0.0000 BUT E_gamma=12.999E-2 => part/pr=9.9999960E-1
> E_gamma=14.75E-2 => part/pr=0.0000 BUT E_gamma=14.75001E-2 => part/pr=9.9999990E-1
>
> I guess, since 13.0E-2 MeV is "almost" equal to 12.999E-2 MeV, the resultant part/pr value will "almost" be the same. But I wonder what the reason is for such a situation. Is it a bug or a rounding matter?
>
> Many thanks.
>
> Dr. Hakan AKYILDIRIM
> University of Süleyman Demirel
> Dept. of Physics/Nuclear Physics
> TURKEY
>
Received on Tue Dec 17 2013 - 11:57:49 CET