The EUV Detector Radiometry Beamline (BL-9) is devoted to detector-based radiometry and other measurements of optical properties in the extreme ultraviolet (EUV) from 5 nm to 50 nm wavelength (25 eV to 250 eV photon energy).
The beamline consists of a grazing-incidence, torroidal-grating monochromator equipped with two diffraction gratings. The gratings are mounted back-to-back, and either one can be selected for use without breaking vacuum. The first grating is ruled with 1200 lines per millimeter and is used from 5 nm to 17 nm. The second grating is ruled with 300 lines per millimeter and is covers the range from 14 nm to 50 nm.
The beamline is equipped with a set of thin-film filters for spectral filtering: C, B, Be, Al, and Mg. Additional high-diffraction order suppression is achieved by operating SURF III at different energies for different wavelength regions. SURF is operated at 183 MeV when measuring at the longest wavelengths. the energy is progressively raised to 361 MeV at the shortest wavelengths. the combination of filters and electron energy selection nearly eliminates high diffraction orders from the monochromator exit beam.
The end station instrumentation includes a single-plate ionization chamber and a 4-axis (X, Y, Z, Θ) stage for mounting up to eight photodiode detectors or four filters for measurement. Additionally, an X-Y stage and photodiode can be mounted at the rear of the beamline.