COMPOSITE GERMANIUM MONOCHROMATORS - RESULTS FOR THE TRICS SINGLE-CRYSTAL DIFFRACTOMETER AT SINQ

Composite germanium monochromators are foremost in application in neut ron diffraction due to their good scattering properties, low absorptio n values and the diamond structure which avoids second-order contamina tion when using hkk reflections (all odd). Our slices for the monochro mator are built from 24 wafers, each 0.4 mm thick. The alignment of th e wafers within the final composite wafer package has been improved by adding tin for the soldering process with a sputtering method instead of foils. Nine slices, each 12.5 mm high, are mounted on separate min iature goniometer heads to the focusing monochromator. The focusing an gle is controlled by only one motor!digitizer by using a sophisticated mechanism. Turning the monochromator by 9 degrees around a allows acc ess of the 311 (primary) and 511 (secondary) reflection. We also show the importance of permanent quality control with neutrons. The monochr omator will be used on the single-crystal diffractometer TriCS at SINQ . (C) 1998 Elsevier Science B.V. All rights reserved.