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/*******************************************************************************
*
* McStas, neutron ray-tracing package
* Copyright 1997-2002, All rights reserved
* Risoe National Laboratory, Roskilde, Denmark
* Institut Laue Langevin, Grenoble, France
*
* Component: Beamstop
*
* %ID
*
* Written by: Kristian Nielsen
* Date: January 2000
* Origin: Risoe
*
* Rectangular/circular beam stop.
*
* %D
* A simple rectangular or circular beam stop.
* Infinitely thin and infinitely absorbing.
* The beam stop is by default rectangular. You may either
* specify the radius (circular shape), or the rectangular bounds.
*
* Example: Beamstop(xmin=-0.05, xmax=0.05, ymin=-0.05, ymax=0.05)
* Beamstop(radius=0.1)
*
* %PAR
*
* INPUT PARAMETERS
*
* radius: [m] radius of the beam stop in the z=0 plane, centered at Origo
* xmin: [m] Lower x bound
* xmax: [m] Upper x bound
* ymin: [m] Lower y bound
* ymax: [m] Upper y bound
* xwidth: [m] Width of beamstop (x). Overrides xmin, xmax.
* yheight: [m] Height of beamstop (y). Overrides ymin, ymax.
*
* %END
*******************************************************************************/
DEFINE COMPONENT Beamstop
SETTING PARAMETERS (xmin=-0.05, xmax=0.05, ymin=-0.05, ymax=0.05,
xwidth=0, yheight=0, radius=0)
/* Neutron parameters: (x,y,z,vx,vy,vz,t,sx,sy,sz,p) */
INITIALIZE
%{
if (xwidth > 0) { xmax = xwidth/2; xmin = -xmax; }
if (yheight > 0) { ymax = yheight/2; ymin = -ymax; }
if (xmin == 0 && xmax == 0 && ymin == 0 & ymax == 0 && radius == 0)
{ fprintf(stderr,"Beamstop: %s: Error: give geometry\n", NAME_CURRENT_COMP); exit(-1); }
%}
TRACE
%{
double Time = t;
ALLOW_BACKPROP;
PROP_Z0;
Time = t - Time;
if ((Time>=0) && ((radius!=0) && (x*x + y*y <= radius*radius))
|| ((Time>=0) && (radius==0) && (x>xmin && x<xmax && y>ymin && y<ymax)))
ABSORB;
else
RESTORE_NEUTRON(INDEX_CURRENT_COMP, x, y, z, vx, vy, vz, t, sx, sy, sz, p);
%}
MCDISPLAY
%{
if (radius != 0)
circle("xy", 0, 0, 0, radius);
else
multiline(5, (double)xmin, (double)ymin, 0.0,
(double)xmax, (double)ymin, 0.0,
(double)xmax, (double)ymax, 0.0,
(double)xmin, (double)ymax, 0.0,
(double)xmin, (double)ymin, 0.0);
%}
END
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