A neutron reflectometer with horizontal sample geometry at CARR

A neutron reflectometer with horizontal sample geometry has been developed by the Institute of Chemistry, Chinese Academy of Sciences (ICCAS), and recently installed at China Advanced Research Reactor (CARR) under the participating research team agreement with China Institute of Atomic Energy (CIAE). This instrument is the first neutron reflectometer in China, and is dedicated to the structural characterization of thin films and multilayers of soft matter. For the cold neutron source and curved guide, the feasible wavelength of the incident neutron beam is 4.75 Å monochromated by pyrolytic graphite crystals, and this permits the scattering vector Q ranging from -0.23 to 0.4 Å−1. This instrument is equipped with a 3He point detector to measure the incident neutron beam and a 3He point detector or linear position sensitive detector to detect the reflected neutron beam. It allows a step-by-step measurement by isochronously changing the incident and reflective angles, and also can be treated as a simple optical imaging element simultaneously measuring neutron reflectivity of multi incident angles using a loosely collimated beam in the absence of significant off-specular scattering. A detailed description of this flexible instrument and its performance characteristics are given.