Re: how to describe ISO and ROT sources

From: Anna Ferrari <anna.ferrari_at_lnf.infn.it>
Date: Mon, 6 Sep 2010 15:31:52 +0200 (CEST)

Dear Zhixi Yue,

 I think that a quite simple way to describe a rotational geometry like
yours (I assume that you have only a spherical isotropic source and your
cylinder) is to use a source, that rotates itself around the cylinder. In
this way the problem is reduced to the description of a source that
generates an isotropic fluence across a sphere of 40 cm radius, with the
center that is uniformly sampled from a circumference around the
cylinder.

To know more about the subroutine source I would suggest to read, as first
step, this FLUKA lesson:
 https://www.fluka.org/free_download/course/demokritos2009/Lectures/UserRoutines0409.pdf

Then looking at pag.20-21 you should understand what you have to modify in
your case in the fortran code.
You have to assign by yourself the direction cosines (TXFLK, TYFLK, TZFLK)
and the initial space coordinates (XFLK, YFLK, ZFLK).
How to do it? At pag. 22-23 you find first of all the list of the random
number generators that you are allowed to use (to save the history
reproducibility you have to use only these) and a useful list of routines.
Between these routines I read (I also never used it) that the SFLOOD
routine, via the call:
 CALL SFLOOD ( XXX, YYY, ZZZ, UXXX, VYYY, WZZZ )
returns:
  - in XXX, YYY, ZZZ a random position on the surface of a sphere of
radius 1 and centre 0;
  - in UXXX, VYYY, WZZZ the random cosines distributed in order to
generate a uniform and isotropic fluence inside the sphere.
UXXX,VXXX,WZZZ give you therefore immediatly the direction cosines.

To obtain from XXX, YYY, ZZZ the initial coordinates you have to:
 - multiply it by the sphere radius (40 cm);
 - add the coordinates of the center of the sphere. To obtain a value
correctly sampled you can use for example the routine SFECFE, that via
the call:
   CALL SFECFE (SINT,COST)
returns SINT and COST, sine and cosine of a random azimuthal angle.
If you put your coordinate system in the center of your cylinder, with the
z axis along the cylinder axis, you obtain for the coordinates of the
center of the source sphere something like X_0=d*SINT,Y_0=d*COST, Z_0=0.,
where d is the distance between the cylinder axis and the center of your
source.

 I think it should work...

 Hope it helps,
 regards,

 Anna

> I am a new learner. I want to describe a isotropic source(ISO) and
> rotational
> geometry(ROT). The former is a sphereal surface(radius 40cm), and the
> latter is a
> cylindrial surface(radius 40cm and high 30cm). The subroutine SOURCE is
> needed. I
> have carefully looked the source.f file. But I still doní»t know how to
> discribe
> the sphereal geometry, and even have not found where to be changed and
> added the
> fortran codes.
> Any help is thankful.
> Thanks
> Zhixi yue
>
>
>
Received on Mon Sep 06 2010 - 16:05:08 CEST

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