Application of a stacked elastically bent perfect Si monochromator with identical and different crystallographic planes for single crystal and powder neutron diffractometry

In order to obtain more neutrons at the sample position, two Si(1 1 1) plates of W250 x H40 x T5 mm(3) were stacked and currently succeeded in increasing the flux at the sample position of BIX-III diffractometer with JRR-3M at JAERI, Japan by a factor of 1.6 compared to that of a single Si plate. To improve the data taking efficiency, preliminarily, a multi-wavelength monochromator system of stacked elastically bent perfect Si(1 1 1) and Si(2 2 0) crystals was employed to carry out diffraction experiments of Si powder and a relatively complex single crystal, piperidine cobaloxime. Two wavelengths, lambda(1) = 1.80 Angstrom for Si(2 2 0) and lambda(2) = 2.94 Angstrom for Si(1 1 1) were selected for this experiment. All reflections were collected by a neutron imaging plate detector, and the profiles were found to be symmetric and well defined Gaussians. (C) 2000 Elsevier Science B.V. All rights reserved.