Neutron Interferometry and Optics Facilities

The Neutron Interferometry and Optics Facilities are located at the NIST Center for Neutron Research. They are one of the world's premier facilities for neutron interferometry and related optical measurements. A neutron interferometer splits, then recombines neutron waves. This gives the interferometer its unique ability to experimentally access the phase of neutron waves. Phase measurements are used to study the magnetic, nuclear, and structural properties of materials, as well as tackle fundamental questions in physics. Related, innovative neutron optical techniques for use in condensed matter and materials science research are being developed. The facilities employ several different interferometers (see figure 1) in order to support this wide breadth of applications.

There are two single crystal neutron interferometry facilities that can operate concurrently. The larger and older of the two is distinguished by the Hutch (see figure 2), a large enclosure to eliminate backgrounds and improve phase stability. To provide neutrons to the inside of the Hutch, neutrons are extracted from a dual-crystal parallel-tracking monochromator system. The sensitivity of the apparatus is greatly enhanced by state-of-the-art thermal, acoustical and vibration isolation systems. To reduce vibration, the Hutch is built on its own foundation, separate from the rest of the building. The position of the inner hutch weighting 40,000 kg is maintained to high precision by a computer-controlled feedback system. The result is a facility with exceptional phase stability and high fringe visibility.

Figure 3 shows the second neutron interferometer facility. Neutrons with a fixed 0.44 nm wavelength are reflected into the experimental area. The interferometer is housed in an aluminum box. Although not as phase stable as the Hutch, this fixed wavelength facility allows greater access and more customizable setups. This includes the use of cryostat and other sample environment components to explore sample characteristics not easily measured at other neutron instruments.