Bragg prism monochromator and analyser for super ultra-small angle neutron scattering studies

摘要

We have designed, fabricated and operated a novel Bragg prism monochromatora€“analyser combination. With a judicious choice of the Bragg reflection, its asymmetry and the apex angle of the silicon single crystal prism, the monochromator has produced a neutron beam with sub-arcsec collimation. A Bragg prism analyser with the opposite asymmetry has been tailored to accept a still sharper angular profile. With this optimized monochromatora€“analyser pair, we have attained the narrowest and sharpest neutron angular profile to date. At this facility, we have recorded the first SUSANS spectra spanning wave vector transfers e?‘? a?? 10a?’6 ?…-1 to characterize samples containing agglomerates up to tens of micrometres in size.