Date: Fri, 21 Dec 2018 18:59:45 +0300
Dear Ivan,
There is an error in your source file! Total weight of your particle
spectrum is unity, but you multiply the weight of the source particle by
ENNUM value for some reason.
WTFLK (NPFLKA) = WEIGH(LINE)*ENNUM
The correct expression:
WTFLK (NPFLKA) = WEIGH(LINE)
Best regards,
Mikhail
On 18.12.2018 18:10, Ivan wrote:
>
> Dear FLUKA experts!
>
> I have a problem or misunderstanding in work. I have a geometry -
> cylinder H = 12m, D = 6m, with air inside and aluminum shell 5.55 cm
> thick (see attached input file). And from the sphere of 7m diameter
> inside the sphere alpha particles emitted with fluence spectrum
> (attached user source routine and spectrum) in case that inside will
> be uniform and isotropic fluence of these particles with value
> 1/(pi*R^2). So, in the output secondary proton spectrum inside
> cylinder, I have a "fall" starting from about 100 MeV and up to about
> 400 MeV and same picture for neutrons, I found this confusing, because
> I have results for the same task from MCNPX and it is about the same
> for alpha inside, but protons and neutrons spectra are smooth and
> without these "falls". I just cant believe that physics models can be
> so different and cause this "fall" in spectra and also, I am also not
> sure about my source routine and I tried everything with physics, it
> seems like I don't have a clue now. Also, before this task I did the
> same, but emitting protons on the cylinder using the same way and
> output fits with the results from MCNPX pretty well.
>
> Please help! I am new using FLUKA and seems lack of ideas now...
> Attached: input file, source routine, spectrum, output files (23 -
> protons, 24 - neutrons, 27 - alpha), figures of "fall" for protons and
> neutrons.
>
> Thanks in advance!
> Best regards,
> Ivan Gordeev
>
>
> P. S. Sending this for the third time, just don't know if it is sent
> or not...
>
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(image/jpeg attachment: 2He_0_23_plot.jpg)
(image/jpeg attachment: 2He_0_24_plot.jpg)