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Towards a Detailed Resolution Smearing Kernel for Time-of-Flight Neutron Reflectometers

Published

Author(s)

Andrew Robert John Nelson

Abstract

The 'exact' resolution kernel for a double chopper time-of-flight neutron reflectometer is calculated. A comparison is made between the resolution kernel and the Gaussian approximation formed by adding the variance of the individual wavelength and angular components. In this paper I derive the 'exact' form of the resolution kernel used data from reactor based time-of-flight (TOF)neutron reflectometers. In comparison to monochromatic neutron reflectomers, where the resolution kernel is close to Gaussian, TOF neutron reflectometers can have trapezoidal reslution kernels. This is a consequence of the disc chopper systems used to pulse the beam having a wavelength uncertainty that is rectangular in shape. The effect of using the exact and approximate kernels is compared, with the main effects seen at high Q where the width of the kernel is approximately the same as the width of the features in the reflectivity curve. The difference between the two kernels is greatest when the wavelength and angular components are of different sizes.
Citation
Journal of Applied Crystallography
Volume
46

Keywords

Neutron reflectometry , resolution , time-of-flight

Citation

John, A. (2013), Towards a Detailed Resolution Smearing Kernel for Time-of-Flight Neutron Reflectometers, Journal of Applied Crystallography, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=913668 (Accessed April 18, 2024)
Created October 1, 2013, Updated February 19, 2017