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Are Bragg Peaks Gaussian?



Boualem Hammouda


It is common practice to assume that Bragg scattering peaks have Gaussian shape. The Gaussian shape function is used to perform instrumental smearing corrections. Using Monte Carlo ray tracing simulation, the resolution of a realistic small-angle neutron scattering (SANS) instrument is generated reliably. Including a single crystal sample with large d-spacing, Bragg peaks are produced. Their widths are a reliable measure of the standard deviation of the resolution function. Results show that Bragg peaks are not Gaussian for broad neutron wavelength spreads; they are not even symmetric. Moreover, it was found that the universally accepted instrumental smearing procedure used to analyze SANS data yields results that are in error by at least 10%.
Journal of Research (NIST JRES) - 119.003
Report Number


Ray tracing simulation, McStas, Small-angle neutron scattering, Bragg peaks, resolution function, Gaussian function


Hammouda, B. (2014), Are Bragg Peaks Gaussian?, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed July 14, 2024)


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Created March 12, 2014, Updated November 10, 2018