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Proceedings Paper

Multilayer monochromators and supermirrors for neutron protein crystallography using a quasi-Laue technique
Author(s): Benno P. Schoenborn
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Paper Abstract

The major problem in neutron protein crystallography is the low flux of present neutron sources. The collection of a data set using a conventional rotation technique and a 2D detector takes many weeks. One way to increase the flux at the sample is to increase the wavelength bandwidth. The conventional technique using a standard monochromator like Cu or Be has a typical bandwidth of 1%. A multilayer monochromator can however be tailored to give bandwidth up to 25% or even larger and have an angular acceptance angle of approximately .3%. This can be achieved by a multiple spacing multilayer. In this case the diffraction geometry is such that the reflection in diffraction condition is 'scanned' by the (Delta) (lambda) and not by rotating the reciprocal lattice point through the Ewald sphere. Wavelength bandwidth of 10% satisfy this condition. It is important to tailor the bandwidth to the size needed by the extend of the reciprocal lattice 'point' to minimize background. The intensity of the reflection is proportional to the (Delta) (lambda) r that just covers the width of the reciprocal 'point' while the background is proportional to the full wavelength spread (Delta) (lambda) that hits the crystal. The conventional Laue technique is not suitable since it increases the background by the ratio of (Delta) (lambda) /(Delta) (lambda) r, a ratio that can easily reach multiples of 10.

Paper Details

Date Published: 23 November 1992
PDF: 7 pages
Proc. SPIE 1738, Neutron Optical Devices and Applications, (23 November 1992); doi: 10.1117/12.130630
Show Author Affiliations
Benno P. Schoenborn, Brookhaven National Lab. (United States)

Published in SPIE Proceedings Vol. 1738:
Neutron Optical Devices and Applications
Charles F. Majkrzak; James L. Wood, Editor(s)

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