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Systematic study on the performance of elliptic focusing neutron guides

Rodriguez, Damian LU ; DiJulio, Douglas LU and Bentley, Phillip LU (2016) In Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment 808. p.101-108
Abstract
In neutron scattering experiments there is an increasing trend towards the study of smaller volume samples, which make the use of focusing optics more important. Focusing guide geometries based on conic-sections, such as those with parabolic and elliptic shapes, have been extensively used in both recently built neutron instruments and upgrades of existing hardware. A large fraction of proposed instruments at the European Spallation Source feature the requirement of good performance when measuring on small samples. The optimised design of a focusing system comes after time consuming Monte-Carlo (MC) simulations. Therefore, in order to help reduce the time needed to design such focusing systems, it is necessary to study systematically the... (More)
In neutron scattering experiments there is an increasing trend towards the study of smaller volume samples, which make the use of focusing optics more important. Focusing guide geometries based on conic-sections, such as those with parabolic and elliptic shapes, have been extensively used in both recently built neutron instruments and upgrades of existing hardware. A large fraction of proposed instruments at the European Spallation Source feature the requirement of good performance when measuring on small samples. The optimised design of a focusing system comes after time consuming Monte-Carlo (MC) simulations. Therefore, in order to help reduce the time needed to design such focusing systems, it is necessary to study systematically the performance of focusing guides. In the present work, we perform a theoretical analysis of the focusing properties of neutron beams, and validate them using a combination of Monte-Carlo simulations and Particle Swarm Optimisations (PS0s), where there is a close correspondence between the maximum divergence of the beam and the shape of the guide. The analytical results show that two limits can be considered, which bound a range of conic section shapes that provide optimum performance. Finally, we analyse a more realistic guide example and we give an assessment of the importance of the contribution from multiple reflections in different systems. (C) 2015 Elsevier B.V. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Neutron guides, Focusing optics, Monte-Carlo simulations, Numerical, optimisation
in
Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment
volume
808
pages
101 - 108
publisher
Elsevier
external identifiers
  • wos:000367095600013
  • scopus:84948420998
ISSN
0167-5087
DOI
10.1016/j.nima.2015.11.057
language
English
LU publication?
yes
id
329c7643-ee37-4ec1-9d6e-117483a4bb4a (old id 8539896)
date added to LUP
2016-01-26 11:28:01
date last changed
2017-01-01 05:38:54
@article{329c7643-ee37-4ec1-9d6e-117483a4bb4a,
  abstract     = {In neutron scattering experiments there is an increasing trend towards the study of smaller volume samples, which make the use of focusing optics more important. Focusing guide geometries based on conic-sections, such as those with parabolic and elliptic shapes, have been extensively used in both recently built neutron instruments and upgrades of existing hardware. A large fraction of proposed instruments at the European Spallation Source feature the requirement of good performance when measuring on small samples. The optimised design of a focusing system comes after time consuming Monte-Carlo (MC) simulations. Therefore, in order to help reduce the time needed to design such focusing systems, it is necessary to study systematically the performance of focusing guides. In the present work, we perform a theoretical analysis of the focusing properties of neutron beams, and validate them using a combination of Monte-Carlo simulations and Particle Swarm Optimisations (PS0s), where there is a close correspondence between the maximum divergence of the beam and the shape of the guide. The analytical results show that two limits can be considered, which bound a range of conic section shapes that provide optimum performance. Finally, we analyse a more realistic guide example and we give an assessment of the importance of the contribution from multiple reflections in different systems. (C) 2015 Elsevier B.V. All rights reserved.},
  author       = {Rodriguez, Damian and DiJulio, Douglas and Bentley, Phillip},
  issn         = {0167-5087},
  keyword      = {Neutron guides,Focusing optics,Monte-Carlo simulations,Numerical,optimisation},
  language     = {eng},
  pages        = {101--108},
  publisher    = {Elsevier},
  series       = {Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment},
  title        = {Systematic study on the performance of elliptic focusing neutron guides},
  url          = {http://dx.doi.org/10.1016/j.nima.2015.11.057},
  volume       = {808},
  year         = {2016},
}