A new polarized neutron reflectometer at Dhruva for specular and off-specular neutron reflectivity studies

A polarized neutron reflectometer for vertical sample geometry has been installed in the guide tube laboratory of Dhruva reactor at Trombay, India. The instrument uses a monochromatic neutron beam of 2.5 angstrom in a step scan mode with a linear position sensitive detector for data collection. This allows one to collect off-specular or diffuse neutron reflectivity (DNR) data quite easily besides specular reflectivity data. The design aspects of this instrument have been presented. The instrument can easily switch between unpolarized and polarized mode, since the beam to the sample is prepared by reflection from a polarizing supermirror or a non-polarizing supermirror. Specular reflectivity studies in unpolarized and polarized mode, for chemical and magnetic structure of thin film samples have been presented. DNR data has been collected from a Ni film. Interface morphology at the air-film interface has been obtained from this data.