Multilayer monochromators for neutron spectrometers

Conference · Thu Jan 01 00:00:00 EST 1987

OSTI ID:6246311

Saxena, A M; Schoenborn, B P

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.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6246311
• Report Number(s): BNL-40084; CONF-8708117-2; ON: DE87014291
• 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

Related Subjects

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