Multilayer monochromators for neutron spectrometers

Conference · Thu Jan 01 04:00:00 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
• Country of Publication: United States
• Language: English

Related Subjects

440103* -- Radiation Instrumentation-- Nuclear Spectroscopic Instrumentation
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
BEAMS
BRAGG REFLECTION
COMPUTERIZED CONTROL SYSTEMS
CONTROL SYSTEMS
DEPOSITION
FABRICATION
LAYERS
MEASURING INSTRUMENTS
MIRRORS
MONOCHROMATORS
NEUTRON BEAMS
NEUTRON SPECTROMETERS
NUCLEON BEAMS
OPTICAL PROPERTIES
PARTICLE BEAMS
PERFORMANCE
PHYSICAL PROPERTIES
POLARIZATION
REFLECTION
REFLECTIVITY
SPECTROMETERS
SPUTTERING
SURFACE PROPERTIES