Re: [fluka-discuss]: changing beam direction in source.f

From: Francesc Salvat-Pujol <francesc.salvat.pujol_at_cern.ch>
Date: Mon, 20 Aug 2018 09:53:33 +0200

Dear Alex,

If you find it more comfortable, you can consider adapting something
along the following lines in source.f:

      XSPT = 2.5D+00
      YSPT = 2.5D+00
      XFLK(NPFLKA) = XBEAM
      YFLK(NPFLKA) = YBEAM + (TWOTWO * FLRNDM(YDUMMY) - ONEONE)
     & * YSPT
      ZFLK(NPFLKA) = ZBEAM + (TWOTWO * FLRNDM(ZDUMMY) - ONEONE)
     & * ZSPT

You can set the beam direction either with the BEAMPOS card or with the
TXFLK,TYFLK,TZFLK variables, i.e., something a la:

      TXFLK(NPFLKA) = ONEONE
      TYFLK(NPFLKA) = ZERZER
      TZFLK(NPFLKA) = ZERZER

To be adapted (and tested/debugged...) as needed.

With kind regards,

Cesc

On Sun, Aug 19 2018, at 20:51 +0000, Ševčik Aleksandras wrote:
>
>Dear experts
>
>I'm still looking for the solution for this problem as it looks that
>it's not so straightforward to use BEAMAXES option with source.f, at
>least it doesn't work for me. I think maybe it is possible to define
>the particular size of rectangular beam shape inside the source.f,
>let's say 5x5 cm, so I could avoid using BEAM WHAT(3-5) parameters and
>could use only BEAMPOS card to align it with x axis ? How could I do
>this?
>
>Problem is that I have a complex voxel geometry (head) and I want to
>irradiate the particular spot
>
>Alex
>
>-----Original Message-----
>From: owner-fluka-discuss_at_mi.infn.it <owner-fluka-discuss_at_mi.infn.it> On Behalf Of Ševcik Aleksandras
>Sent: Tuesday, August 14, 2018 12:30
>To: Francesc Salvat-Pujol <francesc.salvat.pujol_at_cern.ch>
>Cc: fluka-discuss_at_fluka.org
>Subject: RE: [fluka-discuss]: changing beam direction in source
>
>Dear Francesc
>
>Kindly thanks for the insights. I totally forgot BEAMAXES option, have never used before. So, I guess it can be applied in this situation even without modifying the source.f ,
>
>Regards
>Alex
>
>-----Original Message-----
>From: Francesc Salvat-Pujol <francesc.salvat.pujol_at_cern.ch>
>Sent: Tuesday, August 14, 2018 10:52
>To: Ševčik Aleksandras <aleksandras.sevcik_at_ktu.edu>
>Cc: fluka-discuss_at_fluka.org
>Subject: Re: [fluka-discuss]: changing beam direction in source.f
>
>Dear Alex,
>
>I could be wrong, but you might be in a situation where Note 4 of the {BEAM} card section of the manual applies:
>
> 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).
>
>I gather your beam is along x and you wanted to pass the (spatial) beam width via WHAT(4) and WHAT(5) of the BEAM card, foreseen for beams along the positive z axis instead, as per the note above in this particular scenario.
>
>You can try to set the beam direction with the TXFLK,TYFLK,TZFLK variables in source.f (mind the normalization to ONEONE).
>
>Hope this is not too far off!
>
>Cheers,
>
>Cesc
>
>On Mon, Aug 13 2018, at 20:41 +0000, Ševčik Aleksandras wrote:
>>
>>Dear experts,
>>
>>I have this source.f (attached) routine which samples and generates rectangular beam. When I use BEAMPOS for defining various angles and starting points, I can see that it distorts the rectangular shape then. For example if I set BEAMPOS x=-110 cosx=1 to make it parallel to x axis (see attached input file) I can see that starting point of the beam does not look like rectangular one (attached jpg). If I use BEAMPOS without angular adjustment, i.e. without setting cos, and only for initial coordinates of the beam point, it works well.
>>Does this mean that angular position of the custom beam must be defined in source.f , not in BEAMPOS ? If yes, what exactly should be added in the source.f to enable the angular adjustment of the custom beam?
>>Thank you,
>>Alex
>
>
>
>
>
>--
>Francesc Salvat Pujol
>CERN-EN/STI
>CH-1211 Geneva 23
>Switzerland
>Tel: +41 22 76 64011
>Fax: +41 22 76 69474

--
Francesc Salvat Pujol
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
Tel: +41 22 76 64011
Fax: +41 22 76 69474
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Received on Mon Aug 20 2018 - 11:34:28 CEST

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