UPGRADE AND RECENT PERFORMANCE OF 24-M SGM AT THE PHOTON FACTORY

Performance of a 24-m spherical grating monochromator is described. This beamline is composed of a prefocusing toroidal mirror, a spherical grating monochromator with a movable exit slit and refocusing mirrors. With a 600-l/mm grating and 50-mu-m slit openings, the resolving power of 5700 was achieved at 45 eV in good agreement with the theoretical prediction. The second-order contribution was estimated from Ne 2p photoelectron yield to be less than 40% of the first order for the spectral range of 30-90 eV and less than 11% for that of 90-160 eV with the grating of 600 l/mm. As to the grating of 1800 l/mm, it was estimated to be less than 31% for the spectral range of 80-90 eV and less than 11% for that of 90-150 eV. A photon flux of congruent-to 5 x 10(12) photons/s is obtainable at 70 eV for the grating of 600 l/mm and that of congruent-to 10(12) photons/s is obtainable at 150 eV for the grating of 1800 l/mm.