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The small-angle neutron scattering spectrometer, SANS-Suanni, of the 20 MW China Mianyang Research Reactor (CMRR), was upgraded recently to improve its performance and anti-risk capability. The major modifications include: (i) installing a new mechanical velocity selector consisting of a rotor with helical slots; (ii) a replacement of the front of the detector tank to decrease the minimum sample-to-detector distance; (iii) installing a laser locator and a set of fixed lenses in collimator chamber. After the modifications, firstly, a higher maximum-q (qmax) can be achieved up to 6.3 nm−1. With the help of rotating the detector tank, qmax can be further increased to 10.5 nm−1. Secondly, a higher neutron flux at sample position up to 1.18 ×107 cm−2s−1 (at neutron wavelength of 0.53 nm) is obtained. Thirdly, a convenient and user-friendly beam center finding operation for environmental devices is available. The actual performance after the modifications is demonstrated with the measurements of standard samples.

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 A at a fixed take-off angle of 120o. An array of 64 equidistant 3He filled proportional counters can acquire diffraction patterns with a large-scale diffraction angle range over 160o. As all the Soller slit collimators of HRND have a collimation angle of 10' and the monochromator has an average mosaicity of 0.359o, HRND obtains a best resolution of about 1.6\textperthousand 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.