Absolute measurement of diffuse scattering: Description of an independent double crystal monochromator and of a versatile six circle goniometer on a synchrotron source
This paper describes a novel six-circle diffractometer dedicated to diffraction and diffuse scattering measurements from single crystals. The goniometer allows also the study of protein structures with a bidimensional detector. This complex instrument is set up on a beam line (bending magnet) at LURE DCI (Orsay, France). A double crystal monochromator provides tuneable radiation from 0.7 to 2.5 Å and a fixed beam exit. The two crystals can be moved independently and the second crystal may focus sagittally. This diffractometer takes advantage of the characteristic features of the synchrotron radiation (high intensity, tunability of wavelength, small vertical divergence) for measuring diffuse scattering.