The high intensity diffractometer for residual stress analysis (HIDRA), a third generation residual stress mapping neutron diffractometer at the high flux isotope reactor.

This paper describes the hardware and software upgrades, operation, and performance of the high intensity diffractometer for residual stress analysis (HIDRA) instrument, a residual stress mapping neutron diffractometer located at the High Flux Isotope Reactor at Oak Ridge National Laboratory in Oak Ridge Tennessee, USA. Following a major upgrade in 2018, the new instrument has a single He multiwire 2D 30 × 30 cm position sensitive detector, yielding a field of view of 17° 2θ. The increase in the field of view (from 4° 2θ) from the previous model instrument has contributed to the tremendous improvement in the out of plane solid angle such that the 3D count rate could be obtained easily.

Mapping of Texture and Phase Fractions in Heterogeneous Stress States during Multiaxial Loading of Biomedical Superelastic NiTi.

Thermoelastic deformation mechanisms in polycrystalline biomedical-grade superelastic NiTi are spatially mapped using in situ neutron diffraction during multiaxial loading and heating. The trigonal R-phase is formed from the cubic phase during cooling to room temperature and subsequently deforms in compression, tension, and torsion. The resulting R-phase variant microstructure from the variant reorientation and detwinning processes are equivalent for the corresponding strain in tension and compression, and the variant microstructure is reversible by isothermal loading.

Probing orientation information using 3-dimensional reciprocal space volume analysis.

The crystallographic texture of polycrystalline materials is the result of how these materials are processed and what external forces materials have experienced. Neutron and X-ray diffraction are standard methods to characterize global crystallographic textures. However, conventional neutron and X-ray texture analyses rely on pole figure inversion routines derived from intensity analysis of individual reflections or powder Rietveld analysis to reconstruct and model the orientation distribution from slices through reciprocal space.

Designing Trials of Disease Modifying Agents for Early and Preclinical Alzheimer's Disease Intervention: What Evidence is Meaningful to Patients, Providers, and Payers?

Background: Drug development for disease modifying agents in Alzheimer's disease (AD) is focused increasingly on targeting underlying pathology in very early stages of AD or in cognitively normal patients at elevated risk of developing dementia due to Alzheimer's. Very early interventional studies of this type have many uncertainties, including whether they can provide the clinical results that payers, providers, and patients will wish to see for decisions. This paper describes an initiative to create greater transparency for researchers to anticipate these decision needs.

Current capabilities of the residual stress diffractometer at the high flux isotope reactor.

The engineering diffractometer 2nd Generation Neutron Residual Stress Facility (NRSF2) at the Oak Ridge National Laboratory's High Flux Isotope Reactor was built specifically for the mapping of residual strains. NRSF2 is optimized to investigate a wide range of engineering materials by providing the user a selection of monochromatic neutron wavelengths to maintain the selected Bragg reflection near 2θ = 90°, which is the optimal scattering geometry for strain mapping. Details of the instrument configuration and operation are presented, and considerations for experimental planning are also discussed.