Performance of a multi-wavelength monochromator system for neutron single-crystal and powder diffraction

Ahmed, F. U.*; Tanaka, Ichiro; Niimura, Nobuo

In order to improve significantly data collection efficiency, the advantages of using multi-wavelengths in single-crystal neutron diffraction as well as in powder neutron diffraction were established by experiments using a stacked monochromator assembly of two elastically bent perfect Si(111) and Si(220) crystals. The TAS-2 spectrometer on JRR-3M at JAERI was employed for these experiments. Each crystal was elastically bent in order to increase the flux density at the sample position. Two wavelengths, 1=1.80 for Si(220) and 2=2.94 for Si(111), were selected. With the neutron imaging plate (NIP) detector, it was possible to aquire multiple reflections simultaneously with better intensity, better statistics and higher spatial resolution with an open geometry. As a single crystal sample an organic compound piperidine cobaloxime was used. For the systems investigated in this study, it was possible to assign unambiguously rings or spots to diffraction by 1 or by 2 in the case of powder and single-crystal diffraction on the NIP.