Performance of the YB₆₆ soft X-ray monochromator crystal at the wiggler beamline of the UVSOR facility

Soft X-ray spectra have been measured using a pair of YB₆₆(400) monochromator crystals at the double-crystal monochromator beamline BL7A of the UVSOR facility, where the wiggler radiation has a magnetic field of 4 T. Deformation of the YB₆₆ crystal due to heat load from the synchrotron radiation is almost negligible. The photon flux is about 10⁸ photons s⁻¹ (100 mA)⁻¹ in the energy region 1.2–2 keV and the energy resolution is 0.7 ± 0.1 eV around hν = 1.5 keV. These results show that the YB₆₆ crystal is suitable for use as a monochromator crystal. Its application to soft X-ray spectroscopy is discussed.