Dear Yuanjie BI,
The standard beam direction in FLUKA is the positive z axis. The
geometrical spread of the beam is linked to this direction. See note 4 to
the BEAM card explaination in the MANUAL :
4) All options governed by WHAT(3,4,5) are meaningful only if the beam
direction is along the positive z axis, unless a command BEAMAXES is
issued to establish a beam reference frame different from the geometry
frame (see command BEAMAXES). If the beam is not in the positive z
direction and no BEAMAXES command has been given, WHAT(3)-WHAT(5) must be
set = 0.0 (unpredictable effects would arise otherwise).
You can either redefine the geometry so that the beam is aligned with the
z axis, or issue a BEAMAXES card (see the MANUAL for details) in order to
redefine the beam reference frame.
Regards
Paola
> Dear Fluka experts,
>
> I wrote a circular surface source with R of 11.29, using the BEAM and
> BEAMPOS cards:
>
> BEAM -0.00125 11.29 0.0
> -1.0PHOTON
> BEAMPOS 200. 0.0 0.0 -1. 0.0
> NEGATIVE
>
> But the result is not the same as I expected. When I use USRBIN to record
> the source distribution,
> it gives a strange map as attached in the file. Does anyone know what is
> the problem?
>
>
>
> USRBIN 10. PHOTON -40. 111. 20. 20.tet
> USRBIN 110. -20. -20. 1. 50. 50. &
>
> Many thanks
> Best wishes
> Yuanjie BI
>
>
>
Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
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Received on Wed Jan 21 2015 - 09:36:38 CET