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Title: Multilayer monochromators for neutron spectrometers

Abstract

Multilayer devices have proved to be useful in improving the characteristics of small angle neutron spectrometers. Multilayer monochromators have been fabricated, with d-spacings in the 57 to 200 A range, that have reflectivities greater than 0.95. Multilayer polarizers made of Fe-Ge have similar d-spacings and reflectivities, and polarize the neutron beam with an efficiency approaching unity. It has been shown that the use of neutron guidetubes made of multilayer supermirrors will result in a higher neutron flux at the sample. Present efforts in the fabrication of multilayers are directed towards the following: (1) decreasing the d-spacing while maintaining a high reflectivity, (2) depositing multiple d-spacing monochromators for optimizing the performance of a spectrometer, (3) design and development of supermirror guidetubes. Deposition of such devices requires a precise control on the thickness of each film, with the possibility of changing thicknesses in a predetermined manner. Comparison of theoretical calculations with the diffraction characteristics of multilayers has shown that actual multilayers have significant thickness disorder, which results in a degradation of reflection properties. The number of bilayers required to make a high-reflectivity multilayer increases rapidly with decreasing d-spacing. Even a small amount of random thickness disorder will have a cumulative effect, andmore » this may impose a lower limit on the d-spacing of a useful multilayer.« less

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Lab., Upton, NY (USA)
OSTI Identifier:
6246311
Report Number(s):
BNL-40084; CONF-8708117-2
ON: DE87014291
DOE Contract Number:  
AC02-76CH00016
Resource Type:
Conference
Resource Relation:
Conference: Neutron scattering symposium on advances and applications, Sydney, Australia, 8 Aug 1987; Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; MONOCHROMATORS; FABRICATION; PERFORMANCE; NEUTRON SPECTROMETERS; BRAGG REFLECTION; COMPUTERIZED CONTROL SYSTEMS; DEPOSITION; LAYERS; MIRRORS; NEUTRON BEAMS; POLARIZATION; REFLECTIVITY; SPUTTERING; BEAMS; CONTROL SYSTEMS; MEASURING INSTRUMENTS; NUCLEON BEAMS; OPTICAL PROPERTIES; PARTICLE BEAMS; PHYSICAL PROPERTIES; REFLECTION; SPECTROMETERS; SURFACE PROPERTIES; 440103* - Radiation Instrumentation- Nuclear Spectroscopic Instrumentation

Citation Formats

Saxena, A M, and Schoenborn, B P. Multilayer monochromators for neutron spectrometers. United States: N. p., 1987. Web.
Saxena, A M, & Schoenborn, B P. Multilayer monochromators for neutron spectrometers. United States.
Saxena, A M, and Schoenborn, B P. Thu . "Multilayer monochromators for neutron spectrometers". United States.
@article{osti_6246311,
title = {Multilayer monochromators for neutron spectrometers},
author = {Saxena, A M and Schoenborn, B P},
abstractNote = {Multilayer devices have proved to be useful in improving the characteristics of small angle neutron spectrometers. Multilayer monochromators have been fabricated, with d-spacings in the 57 to 200 A range, that have reflectivities greater than 0.95. Multilayer polarizers made of Fe-Ge have similar d-spacings and reflectivities, and polarize the neutron beam with an efficiency approaching unity. It has been shown that the use of neutron guidetubes made of multilayer supermirrors will result in a higher neutron flux at the sample. Present efforts in the fabrication of multilayers are directed towards the following: (1) decreasing the d-spacing while maintaining a high reflectivity, (2) depositing multiple d-spacing monochromators for optimizing the performance of a spectrometer, (3) design and development of supermirror guidetubes. Deposition of such devices requires a precise control on the thickness of each film, with the possibility of changing thicknesses in a predetermined manner. Comparison of theoretical calculations with the diffraction characteristics of multilayers has shown that actual multilayers have significant thickness disorder, which results in a degradation of reflection properties. The number of bilayers required to make a high-reflectivity multilayer increases rapidly with decreasing d-spacing. Even a small amount of random thickness disorder will have a cumulative effect, and this may impose a lower limit on the d-spacing of a useful multilayer.},
doi = {},
url = {https://www.osti.gov/biblio/6246311}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1987},
month = {1}
}

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