Correction of optical aberrations in elliptic neutron guides
(2012) In Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment 693. p.268-275- Abstract
- Modern, nonlinear ballistic neutron guides are an attractive concept in neutron beam delivery and instrumentation because they offer increased performance over straight or linearly tapered guides. However, like other ballistic geometries they have the potential to create significantly non-trivial instrumental resolution functions. We address the source of the most prominent optical aberration, namely coma, and we show that for extended sources the off-axis rays have a different focal length from on-axis rays, leading to multiple reflections in the guide system. We illustrate how the interplay between coma, sources of finite size, and mirrors with non-perfect reflectivity can therefore conspire to produce uneven distributions in the neutron... (More)
- Modern, nonlinear ballistic neutron guides are an attractive concept in neutron beam delivery and instrumentation because they offer increased performance over straight or linearly tapered guides. However, like other ballistic geometries they have the potential to create significantly non-trivial instrumental resolution functions. We address the source of the most prominent optical aberration, namely coma, and we show that for extended sources the off-axis rays have a different focal length from on-axis rays, leading to multiple reflections in the guide system. We illustrate how the interplay between coma, sources of finite size, and mirrors with non-perfect reflectivity can therefore conspire to produce uneven distributions in the neutron beam divergence, a source of complicated resolution functions. To solve these problems, we propose a hybrid elliptic-parabolic guide geometry. Using this new kind of neutron guide shape, it is possible to condition the neutron beam and remove almost all of the aberrations, whilst providing the same performance in beam current as a standard elliptic neutron guide. We highlight the positive implications for neutron scattering instruments that this new shape can bring. (c) 2012 Elsevier B.V. All rights reserved. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/3382455
- author
- Bentley, Phillip LU ; Kennedy, Shane J. ; Andersen, Ken LU ; Rodriguez, Damian Martin and Mildner, David F. R.
- organization
- publishing date
- 2012
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Neutron guide, Elliptic, Parabolic, Ballistic, Conic section
- in
- Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment
- volume
- 693
- pages
- 268 - 275
- publisher
- Elsevier
- external identifiers
-
- wos:000311008400035
- scopus:84865341225
- ISSN
- 0167-5087
- DOI
- 10.1016/j.nima.2012.07.002
- language
- English
- LU publication?
- yes
- id
- a2a159fa-b4ec-4392-bde1-ad438e3af2c6 (old id 3382455)
- date added to LUP
- 2016-04-01 12:57:44
- date last changed
- 2022-01-27 08:34:50
@article{a2a159fa-b4ec-4392-bde1-ad438e3af2c6,
abstract = {{Modern, nonlinear ballistic neutron guides are an attractive concept in neutron beam delivery and instrumentation because they offer increased performance over straight or linearly tapered guides. However, like other ballistic geometries they have the potential to create significantly non-trivial instrumental resolution functions. We address the source of the most prominent optical aberration, namely coma, and we show that for extended sources the off-axis rays have a different focal length from on-axis rays, leading to multiple reflections in the guide system. We illustrate how the interplay between coma, sources of finite size, and mirrors with non-perfect reflectivity can therefore conspire to produce uneven distributions in the neutron beam divergence, a source of complicated resolution functions. To solve these problems, we propose a hybrid elliptic-parabolic guide geometry. Using this new kind of neutron guide shape, it is possible to condition the neutron beam and remove almost all of the aberrations, whilst providing the same performance in beam current as a standard elliptic neutron guide. We highlight the positive implications for neutron scattering instruments that this new shape can bring. (c) 2012 Elsevier B.V. All rights reserved.}},
author = {{Bentley, Phillip and Kennedy, Shane J. and Andersen, Ken and Rodriguez, Damian Martin and Mildner, David F. R.}},
issn = {{0167-5087}},
keywords = {{Neutron guide; Elliptic; Parabolic; Ballistic; Conic section}},
language = {{eng}},
pages = {{268--275}},
publisher = {{Elsevier}},
series = {{Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment}},
title = {{Correction of optical aberrations in elliptic neutron guides}},
url = {{http://dx.doi.org/10.1016/j.nima.2012.07.002}},
doi = {{10.1016/j.nima.2012.07.002}},
volume = {{693}},
year = {{2012}},
}