A perfect crystal X-ray analyser with meV energy resolution

European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble, Cedex, France; Università di L'Aquila, I-67100 L'Aquila, Italy; Istituto Nazionale di Fisica della Materia, I-67100 L'Aquila, Italy
Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms (Impact Factor: 1.19). 04/1996; DOI: 10.1016/0168-583X(95)01288-5

ABSTRACT We present a new method to construct a spherical crystal X-ray energy analyser. The energy analysis is based on high order Bragg reflections from a silicon perfect crystal at angles very close to 90°. In order to preserve the perfect crystal properties in a focusing optics, necessary for meV energy resolution and large angular acceptance, we developed a procedure to mount ≈12 000 small crystals, obtained from the same silicon wafer, on a spherical substrate. The method is based on computer controlled glueing and cycles of etching for each crystal. We obtained analysers with an energy resolution of 1.7±0.5 meV for 21.75 keV X-rays, using the Si(11 11 11) reflection, and with 25 mrad2 angular acceptance. These analysers have been specifically developed for high energy resolution inelastic X-ray scattering.