Dear FLUKA user,
judging from your input file and your email, I understand that you start a
proton beam of 100 MeV inside a cylinder of a Lead-Bismuth-mixture, and
you want to score the neutrons emerging from that cylinder.
To make your input run, I had to change the old FLAIR epression
!_at_what.6=pi*2.5*2.5
to the new FLUKA expression
#define area Pipipi*2.5*2.5*2.+2.*Pipipi*2.5*1.8
and then use the variable "$area" in the WHAT(6) of the USRBDX cards
(I also put the full cylinder surface, not
only one circular base - if you want to treat the different cylinder
surfaces individually, you can divide the TALLY region in three individual
regions such that there is a well defined transition between e.g. the
upper cylinder base and the corresponding TALLY1 region und then use 3
scorers to get individual neutron distributions).
Also some of the LOW-MAT cards had some formatting problems ("LLEAD"
instead of "LEAD").
To score the emerging neutron fluence in neutrons/cm2, you can use
the USRBDX scorer, but keep in mind that this will give the double
differential fluence in energy and solid angle, in units of cm-2 GeV-1
sr-1. So you should multiply the results by the width of the bin in energy
and by 2pi/3 (since you are requesting 3 intervals in solid angle). Scoring
"phi1, LogE, LinOmega" (like you do in your input) should indeed
reproduce a MCNP f2 tally.
The width of the bin can be obtained from the tab.lis file which is
produced running the $FLUPRO/flutil/usxsuw program over the fort_xx -files
produced by the FLUKA runs.
USRYIELD would give a f1-like-tally, however, you seem to use it for point
target yields (putting WHAT(4) = -1.0 and WHAT(5) = -2.0), which is maybe not
what you'd want. To get the double differential yield, you have to put the
regions which make the boundary into WHAT(4) and WHAT(5). Again, make sure
to multiply by the energy bin width and the solid angle interval (4pi in
your case).
Cheers,
Stefan
--
Stefan E. Mueller
Department of Information Services and Computing - Computational Science
and Institute of Radiation Physics
Helmholtz-Zentrum Dresden-Rossendorf
Tel: +49 (0351) 260 3847
Stefan.Mueller_at_hzdr.de
http://www.hzdr.de
Vorstand: Prof. Dr. Sebastian M. Schmidt, Dr. Diana Stiller
Vereinsregister: VR 1693 beim Amtsgericht Dresden
On Mon, 1 Mar 2021, ytaiwo85_at_mail.ustc.edu.cn wrote:
> Dear Expert
> I am a beginner who is trying to study the neutron leakage from a PbBi
> target when bombard with 100MeV proton beam.i.e (mean free path of proton
> beams inside the target material)
> I used usryield and usrbxd cards to score neutron leakage. I want to use the
> result to define fixed source (sdef) in mcnp as my studies is on ADS. I need
> result similar to F2 card in mcnp.
> I don't know if i am doing it right or wrong. Kindly help to have a look at
> attached input file.
> thank you
>
>
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Received on Tue Mar 02 2021 - 11:39:04 CET