IMPROVEMENT OF THE DOUBLE-CRYSTAL DIFFRACTOMETER AT THE GEESTHACHT NEUTRON FACILITY (GENF) BY MEANS OF PERFECT CHANNEL-CUT SILICON-CRYSTALS

High resolution small-angle neutron scattering (HR-SANS) investigation s have been performed by means of the double crystal diffractometer (D CD) at the Geesthacht Neutron Facility (GeNF). The two single perfect silicon crystals of the instrument have recently been replaced by chan nel-cut ones in the non-dispersive (1, - 1) setting to reduce the inte nsity of the rocking curve in its wings by three-fold reflections. The reby a very strong decrease of this intensity has been achieved, where by its former dependence on the scattering Vector q of q(-2) has been changed to q(-6). This improvement of the rocking curve leading to a r eduction of the inherent background is presented, and a new perspectiv e for future HR-SANS investigations is pointed out. (C) 1998 Elsevier Science B.V. All rights reserved.