A neutron-velocity selector is a device that allows neutrons of defined velocity to pass while absorbing all other neutrons, to produce a monochromatic neutron beam. It has the appearance of a many-bladed turbine. The blades are coated with a strongly neutron-absorbing material, such as Boron-10.
Neutron-velocity selectors are commonly used in neutron research facility to produce a monochromatic beam of neutrons. Due to physical limitations of materials and motors, limiting the maximum speed of rotation of the blades, these devices are only useful for relatively slow neutrons.
- C. D. Clark; E. W. J. Mitchell; D. W. Palmer; I. H. Wilson (1966). "The design of a velocity selector for long wavelength neutrons" (PDF). Journal of Scientific Instruments. 43 (1): 1–5. Bibcode:1966JScI...43....1C. doi:10.1088/0950-7671/43/1/302. Retrieved 31 December 2009.