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Proceedings Paper

Monolithic polycapillary focusing optic for polychromatic neutron diffraction applications
Author(s): David F. R. Mildner; Huaiyu Heather Chen-Mayer; Walter M. Gibson; Arthur J. Schultz
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Paper Abstract

The relatively low flux from neutron sources means that structural analysis using neutron diffraction requires large crystals that are often not available.We are exploring the possibilities of a polycapillary focusing optic to produce a small intense beam spot of size ⪅0.5 mm for small crystals.We have conducted measurements at five different thermal neutron wavelengths to determine the transmission characteristics of a tapered monolithic focusing lens with a focal length of 100 mm,suitable for time-of-flight diffraction.Both the width of the focused beam and the intensity gain of the optic increase as a function of wavelength.We have performed similar measurements on a polychromatic beam on a pulsed neutron source,where the results are subject to background from short wavelength neutrons.The use of a beryllium filter shows the increased effective gain for the longer wavelengths at the expense of an increased focused beam width by a factor of two.In a diffraction measurement from an alpha quartz crystal using a 2.1° convergent beam from a pulsed neutron source,we observed six diffraction peaks in the 1.5 Å -4 Å wavelength bandwidth transmitted by the optic.These diffraction spots show an intensity gain of 5.8 ±0.9 compared to a direct beam diffracting from the same sample volume as that illuminated by the convergent beam.

Paper Details

Date Published: 18 November 2002
PDF: 10 pages
Proc. SPIE 4785, Advances in Neutron Scattering Instrumentation, (18 November 2002); doi: 10.1117/12.452286
Show Author Affiliations
David F. R. Mildner, National Institute of Standards and Technology (United States)
Huaiyu Heather Chen-Mayer, National Institute of Standards and Technology (United States)
Walter M. Gibson, X-Ray Optical Systems, Inc. (United States)
Arthur J. Schultz, Argonne National Lab. (United States)

Published in SPIE Proceedings Vol. 4785:
Advances in Neutron Scattering Instrumentation
Ian S. Anderson; Bruno Guérard, Editor(s)

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