Constraining neutron guide optimizations with phase-space considerations.
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| Title: | Constraining neutron guide optimizations with phase-space considerations. |
|---|---|
| Authors: | Bertelsen, Mads1 mads.bertelsen@gmail.com, Lefmann, Kim1 |
| Source: | Nuclear Instruments & Methods in Physics Research Section A. Sep2016, Vol. 830, p313-324. 12p. |
| Subjects: | Neutron guides, Neutron transport theory, Neutron optics, Phase space, Mathematical optimization |
| Abstract: | We introduce a method named the Minimalist Principle that serves to reduce the parameter space for neutron guide optimization when the required beam divergence is limited. The reduced parameter space will restrict the optimization to guides with a minimal neutron intake that are still theoretically able to deliver the maximal possible performance. The geometrical constraints are derived using phase-space propagation from moderator to guide and from guide to sample, while assuming that the optimized guides will achieve perfect transport of the limited neutron intake. Guide systems optimized using these constraints are shown to provide performance close to guides optimized without any constraints, however the divergence received at the sample is limited to the desired interval, even when the neutron transport is not limited by the supermirrors used in the guide. As the constraints strongly limit the parameter space for the optimizer, two control parameters are introduced that can be used to adjust the selected subspace, effectively balancing between maximizing neutron transport and avoiding background from unnecessary neutrons. One parameter is needed to describe the expected focusing abilities of the guide to be optimized, going from perfectly focusing to no correlation between position and velocity. The second parameter controls neutron intake into the guide, so that one can select exactly how aggressively the background should be limited. We show examples of guides optimized using these constraints which demonstrates the higher signal to noise than conventional optimizations. Furthermore the parameter controlling neutron intake is explored which shows that the simulated optimal neutron intake is close to the analytically predicted, when assuming that the guide is dominated by multiple scattering events. [ABSTRACT FROM AUTHOR] |
| Copyright of Nuclear Instruments & Methods in Physics Research Section A is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 116962820 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Constraining neutron guide optimizations with phase-space considerations. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Bertelsen%2C+Mads%22">Bertelsen, Mads</searchLink><relatesTo>1</relatesTo><i> mads.bertelsen@gmail.com</i><br /><searchLink fieldCode="AR" term="%22Lefmann%2C+Kim%22">Lefmann, Kim</searchLink><relatesTo>1</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Nuclear+Instruments+%26+Methods+in+Physics+Research+Section+A%22">Nuclear Instruments & Methods in Physics Research Section A</searchLink>. Sep2016, Vol. 830, p313-324. 12p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Neutron+guides%22">Neutron guides</searchLink><br /><searchLink fieldCode="DE" term="%22Neutron+transport+theory%22">Neutron transport theory</searchLink><br /><searchLink fieldCode="DE" term="%22Neutron+optics%22">Neutron optics</searchLink><br /><searchLink fieldCode="DE" term="%22Phase+space%22">Phase space</searchLink><br /><searchLink fieldCode="DE" term="%22Mathematical+optimization%22">Mathematical optimization</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: We introduce a method named the Minimalist Principle that serves to reduce the parameter space for neutron guide optimization when the required beam divergence is limited. The reduced parameter space will restrict the optimization to guides with a minimal neutron intake that are still theoretically able to deliver the maximal possible performance. The geometrical constraints are derived using phase-space propagation from moderator to guide and from guide to sample, while assuming that the optimized guides will achieve perfect transport of the limited neutron intake. Guide systems optimized using these constraints are shown to provide performance close to guides optimized without any constraints, however the divergence received at the sample is limited to the desired interval, even when the neutron transport is not limited by the supermirrors used in the guide. As the constraints strongly limit the parameter space for the optimizer, two control parameters are introduced that can be used to adjust the selected subspace, effectively balancing between maximizing neutron transport and avoiding background from unnecessary neutrons. One parameter is needed to describe the expected focusing abilities of the guide to be optimized, going from perfectly focusing to no correlation between position and velocity. The second parameter controls neutron intake into the guide, so that one can select exactly how aggressively the background should be limited. We show examples of guides optimized using these constraints which demonstrates the higher signal to noise than conventional optimizations. Furthermore the parameter controlling neutron intake is explored which shows that the simulated optimal neutron intake is close to the analytically predicted, when assuming that the guide is dominated by multiple scattering events. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Nuclear Instruments & Methods in Physics Research Section A is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.nima.2016.06.003 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 12 StartPage: 313 Subjects: – SubjectFull: Neutron guides Type: general – SubjectFull: Neutron transport theory Type: general – SubjectFull: Neutron optics Type: general – SubjectFull: Phase space Type: general – SubjectFull: Mathematical optimization Type: general Titles: – TitleFull: Constraining neutron guide optimizations with phase-space considerations. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Bertelsen, Mads – PersonEntity: Name: NameFull: Lefmann, Kim IsPartOfRelationships: – BibEntity: Dates: – D: 11 M: 09 Text: Sep2016 Type: published Y: 2016 Identifiers: – Type: issn-print Value: 01689002 Numbering: – Type: volume Value: 830 Titles: – TitleFull: Nuclear Instruments & Methods in Physics Research Section A Type: main |
| ResultId | 1 |
