EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
Collimators
Two types of collimators are defined:
label: ECOLLIMATOR,TYPE=name,L=real,XSIZE=real,YSIZE=real;
label: RCOLLIMATOR,TYPE=name,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 straight reference system
for a collimator is a cartesian coordinate system.
NOTE: When a collimator is displaced transversally in order to model
an asymmetric collimator, particle losses in tracking are reported with
respect to the displaced reference system, not with respect to the
surrounding beam line.
hansg,
January 24, 1997