A new parafocusing paradigm for X-ray diffraction

Danae Prokopiou; James McGovern; Gareth Davies; Simon Godber; Paul Evans; Anthony Dicken; Keith Rogers

doi:10.1107/S1600576720008651

A new parafocusing paradigm for X-ray diffraction

J Appl Crystallogr. 2020 Jul 24;53(Pt 4):1073-1079. doi: 10.1107/S1600576720008651. eCollection 2020 Aug 1.

Authors

Danae Prokopiou¹, James McGovern¹, Gareth Davies¹, Simon Godber², Paul Evans³, Anthony Dicken³, Keith Rogers¹

Affiliations

¹ Cranfield Forensic Institute, Cranfield University, Shrivenham SN6 8LA, UK.
² HALO X-ray Technologies, Nottingham Trent University, Nottingham NG11 8NS, UK.
³ The Imaging Science Group, Nottingham Trent University, Nottingham NG11 8NS, UK.

Abstract

A new approach to parafocusing X-ray diffraction implemented with an annular incident beam is demonstrated for the first time. The method exploits an elliptical specimen path on a flat sample to produce relatively high intensity maxima that can be measured with a point detector. It is shown that the flat-specimen approximation tolerated by conventional Bragg-Brentano geometries is not required. A theoretical framework, simulations and experimental results for both angular- and energy-dispersive measurement modes are presented and the scattering signatures compared with data obtained with a conventional pencil-beam arrangement.

Keywords: Bragg–Brentano geometry; conical incident beams; focal construct geometry; powder X-ray diffraction.

Grants and funding

This work was funded by U.S. Department of Homeland Security, Science and Technology Directorate grant HSHQDC-15-CB0036. Wolfson Foundation grant RSWF\R1\180012. Engineering and Physical Sciences Research Council grant EP/R024316/1.