Speaker
Description
Engineering diffractometers at reactor neutron sources typically use monochromatic beams and scan detectors through 2θ to measure selected Bragg reflections. Because the scattering angle varies among reflections, this geometry can produce asymmetric, reflection-dependent gauge volumes. In contrast, time-of-flight engineering diffractometers commonly use detector banks fixed near 90°, providing a consistent gauge-volume geometry across multiple reflections. Reproducing this fixed-angle configuration at a reactor source requires a polychromatic incident beam coupled with analyzer-detector pairs. Focusing analyzers positioned at approximately ±90^∘ define a fixed gauge volume. Multiplexing is demonstrated by arranging multiple analyzer–detector pairs sequentially, with each analyzer tuned to a selected Bragg reflection and its curvature set to satisfy the focusing condition for the specific analyzer–detector geometry. In this poster, we present a proof-of-concept demonstration of this instrument configuration at the MIT Reactor. We verified the focusing condition for bent-perfect silicon analyzers and demonstrated diffraction measurements from graphite using two in-line analyzers.
Key Words
Polychromatic
Stress-strain
Multiplexing
Focusing
Bent-perfect crystal