Multilayer X-ray optics at CHESS

Almost half of the X-ray beamlines at the Cornell High Energy Synchrotron Source ( CHESS) are based on multilayer optics. `Traditional' multilayers with an energy resolution of Delta E/E similar or equal to 2% are routinely used to deliver X-ray flux enhanced by a factor of 10(2) in comparison with standard Si(111) optics. Sagittal-focusing multilayers with fixed radius provide an additional factor of 10 gain in flux density. High-resolution multilayer optics with Delta E/E similar or equal to 0.2% are now routinely used by MacCHESS crystallographers. New wide-bandpass multilayers with Delta E/E = 5% and 10% have been designed and tested for potential applications in macromolecular crystallography. Small d-spacing multilayers with d <= 20 (A) over circle have been successfully used to extend the energy range of multilayer optics. Analysis of the main characteristics of the Mo/B4C and W/B4C small d-spacing multilayer optics shows enhancement in their performance at higher energies. Chemical vapour deposited SiC, with a bulk thermal conductivity of a factor of two higher than that of silicon, has been successfully introduced as a substrate material for multilayer optics. Characteristics of different types of multilayer optics at CHESS beamlines and their applications in a variety of scattering, diffraction and imaging techniques are discussed.