Divergence of neutron microbeams from planar waveguides

TL;DR

This paper discusses the divergence of neutron microbeams generated by planar waveguides, focusing on the diffraction effects influencing their angular width and methods to characterize this divergence.

Contribution

It provides a review of methods to measure and analyze the angular divergence of neutron microbeams from planar waveguides, highlighting the role of Fraunhofer diffraction.

Findings

Fraunhofer diffraction significantly affects microbeam divergence

Various characterization techniques for angular divergence are discussed

Understanding divergence aids in high-resolution microstructure investigations

Abstract

Neutron planar waveguides are focusing devices generating a narrow neutron beam of submicron width. Such a neutron microbeam can be used for the investigation of local microstructures with high spatial resolution. The essential parameter of the microbeam is its angular width. The main contribution to the microbeam angular divergence is Fraunhofer diffraction on a narrow slit. We review and discuss various ways to characterize the angular divergence of the neutron microbeam using time-of-flight and fixed wavelength reflectometers.