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

In order to obtain more neutrons at the sample position, two Si(1 1 1) plat es of W250 x H40 x T5 mm(3) were stacked and currently succeeded in increas ing the flux at the sample position of BIX-III diffractometer with JRR-3M a t 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 mono chromator 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 a nd a relatively complex single crystal, piperidine cobaloxime. Two waveleng ths, 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 colle cted 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 r ights reserved.