Dear Anton,
Thank you for your reply. I realised that deltax/y on WHAT(4)/(5) of the
BEAM card are for the initial beam shape.
I have attached my input file and testsou.f file to make my problems
clear.
I have used BEAMAXES card, because in actual problem, i have to use
voxel phantom in place of 60 x 30 x180 cm3 box.
I want to simulate X-ray beam along negative Y direction. It starts
from a point and then diverge along x and z direction and at a distance
of 180 cm forms a rectangle of 35 x 35 cm2 irradiating the part of box.
I could able to make beam fall on the box as seen in the image1, but i
am not able to give divergence.
Regards,
Minal Y.Nadar
IDS,BARC, Mumbai
On 2018-08-20 22:36, Anton Lechner wrote:
> Dear Minal,
>
> 1. If you look inside the source routine, you can see that the beam
> position as defined by the BEAMPOS card (stored in X/Y/ZBEAM in the
> (BEAMCM) common) are by default assigned to the particle coordinates.
> However, the rotation of the beam reference frame as defined by the
> BEAMAXIS cards is not applied (the routine uses the direction cosines
> given on the BEAMPOS card). The values are however available in the
> (BEAMCM) common (inside BMAXIS(*,*)) and could be applied manually.
> However, in your case the beam axis corresponds to a geometry axis, so
> it is straightforward to define the direction manually; what is a bit
> more complicated is the divergence sampling around this direction ->
> see point 2.
>
> 2. If you use the user source routine, you have to code yourself the
> divergence of the beam, i.e. the divergence you specify on the BEAM
> card is ineffective (although the value is available via the BEAMCM
> common). Apart from that, if you would not have a user routine, the
> correct way to get the divergence sampling around an arbitrary axis
> (in your case the neg. y-axis) is indeed to transform the beam
> reference frame via the BEAMAXIS cards. Then the sampling will be done
> around this axis. So your approach would have been correct in case you
> wouldn't use a custom source routine.
>
> Just a side remark: you should not mix up divergence (i.e. angular
> distribution of the beam) and transverse beam shape at the beam
> position. Divergence is only specified on WHAT(3), whereas the
> deltax/y on WHAT(4)/(5) of the BEAM card concerns the initial beam
> shape.
>
> 3. Hard to judge without input file.
>
> Cheers, Anton
>
> ________________________________________
> From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it]
> on behalf of minalyn_at_barc.gov.in [minalyn_at_barc.gov.in]
> Sent: 20 August 2018 14:01
> To: fluka-discuss_at_fluka.org
> Subject: [fluka-discuss]: simulation of x-ray divergent beam
>
> Dear fluka experts,
>
> I wanted to simulate X-ray beam along negative Y direction. It starts
> from a point and then diverge along x and z direction and at a distance
> of 180 cm forms a rectangle of 35 x 35 cm2.
>
> I have few doubts.
>
> 1. I have to use source.f file to generate X-ray energies. As beam is
> in
> negative y direction, i am using BEAMAXES card along with BEAM and
> BEAMPOS cards. whether the rotation information is again required to be
> given in source.f?
>
> 2. how to give divergent rectangular beam? I have tried giving deltaphi
> for divergence in mrad and deltax and deltay as 17.5 cm, but i want the
> beam diverged in x and z direction.
>
> 3. I tried to plot the output using BEAM-PART of usrbin, but could not
> able to visualise the divergence.
>
> Kindly help.
>
> Regards,
>
> Minal Y.
> IDS, BARC, Mumbai
>
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Received on Tue Aug 21 2018 - 13:14:32 CEST