Collimators

Two types of collimators are defined:

ECOLLIMATOR

Elliptic aperture,

RCOLLIMATOR

Rectangular aperture.

label:ECOLLIMATOR,TYPE=string,APERTURE=real-vector,L=real,
      XSIZE=real,YSIZE=real;
label:RCOLLIMATOR,TYPE=string,APERTURE=real-vector,L=real,
      XSIZE=real,YSIZE=real;

Either type has three real attributes:

L

The collimator length (default: 0 m).

XSIZE

The horizontal half-aperture (default: unlimited).

YSIZE

The vertical half-aperture (default: unlimited).

For elliptic apertures, XSIZE and YSIZE denote the half-axes respectively, for rectangular apertures they denote the half-width of the rectangle. Optically a collimator behaves like a drift space, but during tracking, it also introduces an aperture limit. The aperture is checked at the entrance. If the length is not zero, the aperture is also checked at the exit.

Example:

COLLIM:ECOLLIMATOR,L=0.5,XSIZE=0.01,YSIZE=0.005;

The reference system for a collimator is a Cartesian coordinate system.