Andrew Jones (USC), Rob Vest(NIST)
October 1999
The linear size of the beam from the SURF-III facility at BL-9 was measured by SEM by linear scans of the SEM channel-2 (0-order) detector over the beam. The SEM filter and grating were letf in the instrument for the measurements.
The response of the SEM to linear scans is roughly trapezoidal, as expected for scanning a finite size beam over an aperture (the SEM grating). The size of the base of the trapezoid is B + W, where B is the beam size, and W the aperture width.
SEM Data
Horizontal Scan
| inches counts mm counts — dark
0.250 25 6.3500 0 0.300 38 7.6200 13 0.325 277 8.2550 252 0.350 812 8.8900 787 0.375 1438 9.5250 1413 0.400 2100 10.160 2075 0.425 2689 10.795 2664 0.450 3059 11.430 3034 0.475 2900 12.065 2875 0.500 2410 12.700 2385 0.525 1755 13.335 1730 0.550 1147 13.970 1122 0.575 505 14.605 480 0.600 155 15.240 130 0.625 38 15.875 13 0.650 27 16.510 2 0.700?26?17.780?1 |
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The Beam Geometry was measured in various orientations:
Wavelength (Å)
Orientation
Grating/Aperture (mm)
Beam (mm)
175
Horizontal
4.034
3.1
175
Vertical
3.854
2.313
175
Horizontal
3.917
2.521
175
- Vertical
3.837
2.309
175
Horizontal
3.975
3.1
304
- Vertical
3.821
2.313
304 NO GRATING
-Vertical
5.4
2.675
175 NO GRATING
Horizontal
5.334
3.033