The FSANS instrument is a recently built instrument at the Budapest Neutron Centre site, used for non-destructive study of the nano-structural features of various materials, among them archaeological objects. The studied size range is between 10 nm and 500 nm. Because of its technical characteristics, it is complementary to the Yellow Submarine SANS Instrument.
The FSANS diffractometer covers a Q-range from 0.0003 to 0.03 Å-1 and complementary to the Yellow Submarine SANS instrument allows to probe structures at larger length scales than the pinhole type SANS instrument. The instrument is installed on the bottom section of the curved neutron guide No.3, made of m = 2 supermirrors. The beam time structure is provided by 4 choppers: a counter-rotating pair of pulse definition choppers, one wavelength limiting and one frame overlap chopper. The available wavelength range is 2–16 Å. The width of the wavelength uncertainty can be set by choosing the pulse definition chopper window to 0.3 A° with 8° opening (better resolution mode) or 0.75 A° with 20° opening (higher intensity mode) respectively. The collimation distance is 3.7 m, the sample to detector distance is maximum 4.3 m. Samples from several millimetres to several tens of centimetres in diameter can be placed at the sample position, the beam size can be varied from 4mm (pinhole collimation mode) to 40 mm (focusing mode) in diameter. The scattered neutrons are detected by a 256 Å~ 256 pixels (0.7 mm Å~ 0.7 mm pixel size) two dimensional position sensitive detector filled with 3He gas. Data acquisition is performed in event recording mode.