MPISI: The neutron strain scanner materials probe for internal strain investigations at the SAFARI-1 research reactor

A modern neutron strain scanner instrument with crystallographic texture measurement capability has been established at the SAFARI-1 research reactor. This instrument, MPISI, has been benchmarked against the VAMAS Ring-and-Plug specimen, as well as in high spatial resolution mode using sub-millimeter beams. It is equipped with a double focused Si-multiwafer monochromator, sturdy high-precision sample manipulation stages, adjustable primary and secondary beam apertures interchangeable with radial collimators (RCs) on the secondary beam side and a 300 x 300 mm(2) position sensitive neutron area detector. The RCs facilitate measurement of large specimens and interfaces. Variation in monochromator horizontal curvature allows optimization of the intensity (texture), resolution (peak broadening), or Figure-of-Merit (strain) with an achievable resolution of Delta d/d similar to 3 x 10(-3). An Android based Wi-Fi hand-held control module in conjunction with lasers and theodolites aid with sample positioning and alignment. Data acquisition and control has been standardised on the SINQ Instrument Control Software. In-house developed data reduction software enables: flat field correction, geometric correction, vertical integration, data normalization, peak and entry-curve fitting, as well as multi-dimensional data visualization. Acquiring data against statistical criteria rather than time improves the overall instrument utilisation efficiency.