Re: Unknown error in geometry

From: Alberto Fasso' (Alberto.Fasso@cern.ch)
Date: Wed Apr 02 2003 - 01:14:51 CEST


Indeed, your geometry description is incorrect.
I will try to list a few things which are obviously wrong or
inconsistent, but the main message is that a geometry such as
the one you are trying to describe cannot be done without the use
of the OR operator.

1) Region 1 (blackhole):
         7 -2 4 -6
   that means "the space inside sphere 7, which is outside cylinder 2, on the
   left of plane 4 and on the right of plane 6"
   No point can be at the same time on the left of plane 4 and on the right of
   plane 6: it is the same as saying that its Z coordinate must be both < -5 and
> 66. What you probably wanted was:
   OR 7 -2OR 7 4OR 7 -6

2) Region 2 (vacuum at the beginning):
         2 -1 3 -4 6 -5
   This would mean: "the space inside the wall of a cylindrical shell contained
   between cylinder 2 and cylinder 1, left of plane 3, right of plane 4, left
   of plane 6 and right of plane 5"
   Again, a point cannot be at the same time be left of plane 3 and right of
   plane 5. And it is not clear why you want vacuum only between 2 and 1 and not
   also inside 1. In any case, the space inside cyl. 1, left of plane 3 and
   right of plane 4 remains undefined. What you probably wanted was:
   OR 2 3 -4OR 2 6 -5OR 2 -1 6 -4

  Alberto

On Tue, 1 Apr 2003, Christopher Knievel wrote:

> Dear FLUKA users and authors:
>
> I am having a problem when I run my input with fluka. I am trying to simulate
> an electron beam interacting with a cylindrical aluminum beam stop. The error
> which I receive in the .err file is as follows:
>
> Geofar: Particle in region 3 (cell # 0) in position 5.730835694E+00 9.686117683E+00 3.982049539E+01
> is now causing trouble, requesting a step of 9.549625271E+00 cm
> to direction 1.929431495E-01 7.823632011E-01 5.921830482E-01, error count: 0
> R2: 1.125448149E+01 R3: 4.138037224E+01 cm
> X*U (2D): 8.683787525E+00 X*U (3D): 3.226480986E+01 cm
> X*UOLD(2D): -2.805983023E+00 X*UOLD(3D): 2.332732094E+01 cm
> Kloop: 49, Irsave: 3, Irsav2: 3, error code: -33 Nfrom: 5000
> old direction 4.859413563E-01 -5.772006160E-01 6.562777210E-01, lagain, lstnew, lsense, lsnsct F F F F
> Particle index 7 total energy 7.510855076E-04 GeV Nsurf 0
> Try again to establish the current region moving the particle of a 1.000000000E-06 long step
> We succeeded in saving the particle: current region is n. 3 (cell # 0)
>
> This error continues for many more cycles. In the .out file the error reads as:
>
> 0EXIT BEING CALLED FROM G1, NEXT REGION NOT FOUND.
> IR= 3 XB= 0.57308359E+01 0.96861185E+01 0.39820496E+02 WB= 0.19294315E+00 0.78236320E+00 0.59218305E+00 DIST= 0.48005062E+01
> IRLTGG= 0 SB= 0.57308359E+01 0.96861185E+01 0.39820496E+02 UB= 0.19294315E+00 0.78236320E+00 0.59218305E+00
> PR 10 0.57308359E+01 0.96861185E+01 0.39820496E+02 0.19294315E+00 0.78236320E+00 0.59218305E+00 3
> 3 3 1 -1 1 0 1 54 54 10
> 93 101 1 93 95 4 0 105 10 10
> -0.31547868E+02 0.48005062E+01 0.48005062E+01 0.48005062E+01
>
> I will attach my input file which I used. I understand that the error means
> that the program is having problems tracking the particle from point (x,y,z)
> to point (x',y',z') defined by the directional vectors given above, I just do
> not know what to do to correct the problem. As one can see from my input, the
> beam dump should be 61 cm long and it is enclosed in a cylindrical vacuum
> shell that is 5 cm thick. At least this is what I tried to simulate.
> Transport should also start at the front of the aluminum cylinder, which is
> the coordinate (0,0,0). If anyone could assist me with my problem, it would
> be greatly appreciated.
>
> Sincerely,
>
> Christopher Knievel
> Health, Safety and Environment Assistant
> Canadian Light Source
>
> <<dice.inp.txt>>
>

-- 
Alberto FassÚ
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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