Offspec spin-echo components give delicate manipulation of polarised neutrons to examine small structures with sizes from 10-1000 nanometres in thin film samples. The instrument relies on rotating polarised neutrons in magnetic fields to give extremely high sensitivity and allow the explicit separation of different signals from the sample with very high resolution.
The length scale coverage of Offspec is comparable to those studied by atomic force microscopy, scanning tunnel microscopy and other more invasive surface profiling techniques.
With a primary flight path of 24 m from the grooved solid methane moderator, the instrument is equipped with two high-resolution, two-dimensional position sensitive detectors 4 m from the sample position. Each has an active area 200mm x 300mm and a pixel size of less than 1mm.
The primary detector located in the straight through beam will measure specular and off-specular reflectivity, as well as grazing incidence diffraction such as that observed in the growth of mesoporous films.
The secondary detector is able to move through 90° for measuring in-plane diffraction associated with surface crystalline structure, surface phase transitions and magnetic surface structures.