Perfect Crystal Neutron Interferometer

Neutron Interferometer. A three blade neutron interferometer, machined from a single crystal silicon ingot is shown in two views. A monoenergetic neutron beam is split by the first blade and recombined in the third blade. If a sample is introduced in one of the paths, a phase difference in the wave function is produced, and interference between the recombined beams causes count rate shifts of opposite sign in the two detectors.

The Neutron Interferometer Facility in the Cold Neutron Guide Hall became operational in April 1994. It became available as a National User Facility in September 1996. Phase contrast of up to 88 percent and phase stability of better than five milliradians per day were observed. These performance indications are primarily the result of the advanced vibration isolation and environmental control systems. The interferometer operates inside a double walled enclosure, with the inner room built on a 40,000 kg slab which floats on pneumatic pads above an isolated foundation.