Polychromatic Multiplexing Stress-Strain Diffractometer

The development of new materials for extreme conditions such as high pressure or radiation requires improvements in characterization techniques, especially with in-situ measurements during synthesis. Neutron scattering techniques have been gaining popularity with the development of new smaller neutron sources and new beamline developments at national facilities. Current engineering beamlines with stress-strain diffractometers at national facilities require long measurement times due to the small gauge volumes of samples. We present our development of a stress-strain diffractometer intended to be optimized for improved efficiency compared with current designs at national facilities and to also be suitable for small research reactors such as the MIT Reactor and laboratory-based neutron generators. The diffractometer will utilize a polychromatic neutron beam to illuminate all the lattice planes within the sample simultaneously allowing for a series of bent perfect crystals to be placed after the sample; these crystals will be used as analyzers rather than monochromators. The silicon crystal analyzers are transparent to neutrons, which has the benefit of multiplexing capabilities with analyzers placed in subsequent order with each measuring the strain of a different lattice plane. Multiplexing is also accomplished by placing analyzers at 2θ&lt;font size="1"&gt;s&lt;/font&gt; ≈ ±90°, which allows the strain to be measured in two directions simultaneously. We will present results from both experimental testing and ray-tracing simulations for this instrument configuration and report on the current state of the construction of the prototype instrument at the MIT Reactor.<br/><br/>We acknowledge useful discussions with A. Stoica. This work is supported by the U.S. Department of Energy (DOE), Office of Science, under a Small Business Technology Transfer (STTR) Grant, Grant No. DE-SC0020555.