Development of a cold-neutron reflectometer (CN REF-V) at the HANARO

A new neutron reflectometer, CN REF-V, has been installed in the cold-neutron laboratory building at the HANARO, a research reactor in Korea. The instrument has a vertical scattering plane and uses a constant wavelength of λ = 4.7535 Å, and it is monochromated by using pyrolytic graphite (PG) crystals. Its measurable minimum reflectivity and maximum momentum transfer for typical solid films are 10 -8 and 0.3 Å -1 , respectively. A liquid-nitrogen-cooled beryllium filter is used to remove λ/2 contamination due to the PG (002) crystals. With a gold wire activation analysis method, the neutron flux at its sample position was measured and found to be 5.67 × 10 5 neutrons/cm 2 /s. Reflectivity measurements of thin films were successfully carried out with the instrument. A detailed characterization of the instrument and the results of the reflectivity measurements are described.