Curved–straight neutron guide system with uniform spatial intensity distribution

Published

May 10, 2008

Author(s)

David Mildner, Jeremy Cook

Abstract

The spatial intensity distribution of neutrons emerging from a curved guide is asymmetric, and straight guide sections are sometimes appended to curved guides to make the intensity distribution more nearly uniform. For idealized uniform illumination and in the perfect reflectivity approximation, the spatial-angular acceptance at the exit of the combination can be made exactly uniform for a range of long wavelengths by using a sufficiently long straight section, together with a curved guide whose outer wall coating has a critical angle slightly greater than those of the other guide walls. We refer to this as a "phase space tailoring guide" where the coatings on the inner wall and straight section are used to define the required divergence at the end of the guide. Increasing the critical angle of the outer wall of the curved section reduces the characteristic wavelength of the curved guide as well as the wavelength at which ideal uniformity can be obtained. The outer wall coating need only be of sufficiently high critical angle to fill the transmittable phase space area of the straight guide uniformly to adequately short wavelength.

Citation

Nuclear Instruments & Methods in Physics Research Section A-Accelerators Spectrometers Detectors and Associated Equipment

Volume

592

Issue

3

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.nima.2008.04.049

Local Download

Keywords

Spatial intensity distribution, Phase space tailoring guide, Critical angle for neutron reflection, Curved–straight neutron guide, Angular intensity distributions, Acceptance diagram, Neutron transmission, Beam bender

Citation

Mildner, D. and Cook, J. (2008), Curved–straight neutron guide system with uniform spatial intensity distribution, Nuclear Instruments & Methods in Physics Research Section A-Accelerators Spectrometers Detectors and Associated Equipment, [online], https://doi.org/10.1016/j.nima.2008.04.049, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=960900 (Accessed October 11, 2025)