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Optimal shape of a cold-neutron triple-axis spectrometer

Lefmann, Kim LU ; Filges, U.; Treue, F.; Kirkensgard, J. J. K.; Plesner, B.; Hansen, K. S. and Kleno, K. H. (2011) International Workshop on Neutron Optics In Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 634. p.1-6
Abstract
We have performed a McStas optimization of the primary spectrometer for a generic 40 m long, cold-neutron triple-axis spectrometer with a doubly focusing monochromator. The optimal design contains an elliptically focusing guide, a virtual source point before a low-grade PG monochromator, and non-equidistant focusing at the monochromator. The flux at 5 meV shows a gain factor 12 over the "classical" design with a straight 12 x 3 cm(2), m=2 guide and a vertically focusing PG monochromator. In addition, the energy resolution was found to be improved. This unexpectedly large design improvement agrees with the Liouville theorem and can be understood as the product of many smaller gain factors, combined with a more optimal utilization of the... (More)
We have performed a McStas optimization of the primary spectrometer for a generic 40 m long, cold-neutron triple-axis spectrometer with a doubly focusing monochromator. The optimal design contains an elliptically focusing guide, a virtual source point before a low-grade PG monochromator, and non-equidistant focusing at the monochromator. The flux at 5 meV shows a gain factor 12 over the "classical" design with a straight 12 x 3 cm(2), m=2 guide and a vertically focusing PG monochromator. In addition, the energy resolution was found to be improved. This unexpectedly large design improvement agrees with the Liouville theorem and can be understood as the product of many smaller gain factors, combined with a more optimal utilization of the beam divergence within the guide. Our results may be relevant for a possible upgrade of a number of cold-neutron triple-axis spectrometers and for a possible triple-axis spectrometer at the European Spallation Source. (C) 2010 Elsevier B.V. All rights reserved. (Less)
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author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
Neutron instrumentation, Triple-axis spectrometer, Ray-tracing, simulation
in
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
volume
634
pages
1 - 6
publisher
Elsevier
conference name
International Workshop on Neutron Optics
external identifiers
  • wos:000290355100001
  • scopus:79952987086
ISSN
0168-9002
DOI
10.1016/j.nima.2010.06.273
language
English
LU publication?
yes
id
f438352c-e524-4043-be16-87df50b694e5 (old id 1987652)
date added to LUP
2011-06-29 09:15:38
date last changed
2017-08-20 04:10:33
@inproceedings{f438352c-e524-4043-be16-87df50b694e5,
  abstract     = {We have performed a McStas optimization of the primary spectrometer for a generic 40 m long, cold-neutron triple-axis spectrometer with a doubly focusing monochromator. The optimal design contains an elliptically focusing guide, a virtual source point before a low-grade PG monochromator, and non-equidistant focusing at the monochromator. The flux at 5 meV shows a gain factor 12 over the "classical" design with a straight 12 x 3 cm(2), m=2 guide and a vertically focusing PG monochromator. In addition, the energy resolution was found to be improved. This unexpectedly large design improvement agrees with the Liouville theorem and can be understood as the product of many smaller gain factors, combined with a more optimal utilization of the beam divergence within the guide. Our results may be relevant for a possible upgrade of a number of cold-neutron triple-axis spectrometers and for a possible triple-axis spectrometer at the European Spallation Source. (C) 2010 Elsevier B.V. All rights reserved.},
  author       = {Lefmann, Kim and Filges, U. and Treue, F. and Kirkensgard, J. J. K. and Plesner, B. and Hansen, K. S. and Kleno, K. H.},
  booktitle    = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  issn         = {0168-9002},
  keyword      = {Neutron instrumentation,Triple-axis spectrometer,Ray-tracing,simulation},
  language     = {eng},
  pages        = {1--6},
  publisher    = {Elsevier},
  title        = {Optimal shape of a cold-neutron triple-axis spectrometer},
  url          = {http://dx.doi.org/10.1016/j.nima.2010.06.273},
  volume       = {634},
  year         = {2011},
}