Double-crystal monochromator beam line on the Aladdin 1-GeV storage ring

Abstract

We report the design, construction, and performance of a soft x-ray beam line with accessible photon energy 0.8–4.0 keV at the Synchrotron Radiation Center, University of Wisconsin–Madison. The beam line features an ultrahigh-vacuum (UHV) compatible high-precision double-crystal monochromator (DCM) covering Bragg angles 12°–72°, which was designed and built at the Physical Science Laboratory (PSL), University of Wisconsin–Madison. The monochromatic x rays are focused by a bent cylindrical mirror (Ni-coated fused silica, located 7.5 m from the source) into the experimental chamber (located 5.5 m from the mirror) down to a spot less than 1 mm(h)×3 mm(v). During the initial runs, the DCM used a pair of InSb(111) crystals and covered photon energy 1.75–3.7 keV. At the silicon K edge (1840 eV), the beam line delivered about 4×1011 photons/s with stored electron beam at 100 mA at 1 Gev, among the most intense and stable sources currently available at this energy. The energy resolution is about 0.9 eV at the Si K edge.