High resolution neutron diffractometer HRND at research reactor CMRR

Abstract

The high resolution neutron diffractometer HRND is located at the 20 MW China Mianyang Research Reactor (CMRR), which is a neutron powder diffractometer especially dedicated to crystal and magnetic structure studies for polycrystalline powder samples. A vertical focusing Ge (511) monochromator produce a monochromatic neutron beam with a wavelength of 1.885 Å at a fixed take-off angle of 120̂. An array of 64 equidistant 3He filled proportional counters can acquire diffraction patterns with a large-scale diffraction angle range over 160̂. As all the Soller slit collimators of HRND have a collimation angle of 10′ and the monochromator has an average mosaicity of 0.359̂, HRND obtains a best resolution of about 1.6\ extperthousand based on experiments, which makes the resolution of HRND can compete with the mainstream-level high resolution neutron powder diffractometers in the world. Equipped with a cryostat and a furnace, HRND allows structural characterization in an extremely broad temperature range. The details of the configuration and performance of the instrument are reported along with its specifications and performance assessments in the present paper.