The corresponding line in the configuration file is:
1st collimator (distance, length, hor1, ...
dist L w1
w2 h1 h2
1/R mh mv
rh rv [ nslit
D ]
Parameters in [] are optional. The meaning is illustrated in the figure.
| dist | distance of the entrance openning from the preceding component |
| L | collimator length |
| w1, w2 | widths of the entrance and exit areas |
| h1, h2 | heights of the entrance and exit areas |
| 1/R | curvature of the collimator [m-1] (1/R < 0 in the figure) |
| mh, mv | critical angles for horizontal and vertical reflecting mirrors (*) |
| rh, rv | reflectivities corresponding to mh, mv |
| D | thickness of the lamellae in [mm] (default 0.28 or 0.08 mm) |
| nslit | number of slits (default calculated automatically from ALFn) |
(*) mh, mv are expressed in the units of nat. Ni at l = 1Å.
Whenever mh or mv differes from zero, a file with corresponding lookup table for mirror reflectivity is searched for in the current directory. The naming convention is 'mirrorx.x', where x.x is the critical angle specified as mh or mv.
If corresponding "mirrorx.x" file is not found, a step-function is taken with r(theta)=rh (or rv) for theta lower than the critical angle for given wavelength.
If nslit is missing or equal 0, the number of slits is calculated with respect to the collimator divergence (ALF1 .. ALF4). If ALFn > 500, than no lamellae are considered.
Example:
"mirror4.1" contains the table for supermirror
reflectivity, which will be used any time you specify 4.1 (or 4.14, 4.06
etc.)
as the critical angle for any collimator. (3 columns contain incident angle
theta [Ni nat.] and r(theta) for the two spin states (e.g. polarizing
guide can be simulated in this way).
Caution! This file must contain 1 row as the header and maximum
128 rows with constant increment in theta. All following lines are
ignored, i.e. the reflectivity is considered = 0 for theta>theta(last
row).