The SNS liquids reflectometer

The SNS Liquids Reflectometer [1], installed as one of the first instruments at the Spallation Neutron Source, has now been functional for more than a year. This instrument is designed to view liquid and solid surfaces in specular, off specular, and near-surface small angle scattering geometries. The guide system supplies 2 Å < λ < 16.5 Å neutrons at vertical incident angles ranging from 0° < α_i < 5.5° for free liquid surfaces and up to 45° for solid surfaces. Three bandwidth choppers, synchronized with the spallation source and operating at 15–60 Hz, provide neutrons in bandwidths ranging from 3.5–14 Å at a fixed incident angle onto a sample. The sample stage enables all of the motions necessary for positioning liquid and solid surfaces, while the detector arm directs a position-sensitive detector to view the sample at specular or off specular angles up to 90° and can scan out of the specular plane by up to 30°.