Re: FLUKA: meaning of geometry parameters


To vylet001@mc.duke.edu
From Alberto Fasso' <Alberto.Fasso@cern.ch>
Date Tue, 17 Apr 2001 11:15:39 +0200 (CEST)
cc fluka-discuss@listbox.cern.ch
In-Reply-To <OF64F49A09.A4101065-ON85256A2E.00805C7A@mc.duke.edu >
Reply-To "Alberto Fasso'" <Alberto.Fasso@cern.ch>
Sender owner-fluka-discuss@listbox.cern.ch

On Sat, 14 Apr 2001 vylet001@mc.duke.edu wrote:

> Dear Fluka users,
> 
> I am having trouble with geometry, but many runs with GEOEND ...debug did
> not find
> anything wrong so far. I would appreciate if someone could explain the
> meaning
> of the parameters below. I suspect that some of these are coordinates and
> directionnal
> cosines, but more detailed info would be helpful. If this is documented
> somewhere,
> please let me know. Is IR region number? (Region #1 in my case is a black
> hole).
> 

> 0EXIT BEING CALLED FROM G1, NEXT REGION NOT FOUND.
>  IR= 1 XB=-0.36456044D+06 0.61141094D+06-0.88888880D+06
>  WB=-0.32012556D+00 0.53688887D+00-0.78055747D+00 DIST= 0.14234839D+06
>  IRLTGG= 0 SB=-0.36456044D+06 0.61141094D+06-0.88888880D+06
> UB=-0.32012556D+00 0.53688887D+00-0.78055747D+00
>  PR 10-0.36456044D+06 0.61141094D+06-0.88888880D+06-0.32012556D+00
> 0.53688887D+00-0.78055747D+00 1

>          1         1         1        -5        -4         0         0      
>  18        14        11
>        296       304        22       107       109        15         0      
> 308        10        10
> -0.10000000D+21 0.10000000D+21 0.14234839D+06 0.14234839D+06

Hi Vashek,

IR is indeed the region number, but in general this is not the most
useful piece of information. The message says that there is a problem
when tracking from point XB (XB(1) = x, XB(2) = y, XB(3) = z)
in the direction of vector WB (WB(1) = u, WB(2) = v, WB(3) = w)
by a distance DIST. Therefore, there is something wrong in your geometry
between the points
  x = -0.36456044D+06    x' = x - 0.32012556D+00 * 0.14234839D+06 
  y =  0.61141094D+06    y' = y + 0.53688887D+00 * 0.14234839D+06 
  z = -0.88888880D+06    z' = z - 0.78055747D+00 * 0.14234839D+06

This is not mentioned in any  FLUKA documentation because in general the
FLUKA geometry debugger is sufficient and more friendly. I am surprised
that it did not find the bug in your case: have you tried to change the
mesh? Anyway, this kind of message is part of the standard Combinatorial
Geometry package as implemented in other codes such as MORSE.

Alberto

-- 
Alberto Fassò
CERN-EP/AIP, CH-1211 Geneve 23 (Switzerland)
Phone: (41 22) 767 2398    Fax: (41 22) 767 9480   Alberto.Fasso@cern.ch



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