Multiple Small Angle Scattering
The theory and analysis of SMALL ANGLE NEUTRON SCATTERING is a major research interest in the Reactor Radiation Division. With colleagues from the Ceramics Division, we have paid particular attention to the problem of extracting reliable size information from SANS dominated by copious incoherent multiple scattering (so-called beam broadening) as commonly occurs in early-stage ceramics. The methodology is now known as MSANS.
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Probing Porous Ceramics Using Small-Angle Scattering
Andrew J. Allen and Norman F. Berk, Neutron News 9, 13 (1998).The theory of MSAS for spherical and nonspherical particles with applications to porous ceramics is reviewed.
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Analysis of Small-Angle Scattering Data Dominated by Multiple Scattering
for Systems Containing Eccentrically Shaped Particles and Pores
A. J. Allen and N. F. Berk, J. Appl. Cryst. 27, 878 (1994).The theory of Berk and Hardman-Rhyne for beam broadening from spherical particles is extended to treat the case of nonspherical particles and pores which can be described by spheroidal (oblate and prolate) shapes. The major findings are that the analysis of such scattering in terms of spheres is appropriate for moderately oblate (cigar-shaped) spheroids, with the sphere radius being interpreted as the radius of the circular cross section, but not for prolate (pancake) shapes. It is also found that dyamical scattering (departure from pure diffraction) is more important for spheroids than for spheres.
An extensive bibliography is given
for applications of
beam broadening analysis. See also
New Developments in Multiple Small-Small Neutron Scattering Studies of Advanced Ceramics
A. J. Allen, N. F. Berk, S. Krueger, G. G. Long, H. M. Kerch, and J. Ilavsky, Mat. Res. Soc. Symp. Proc. 376, 347 (1995). -
Analysis of SAS Data Dominated by Multiple Scattering
N. F. Berk and K. A. Hardman-Rhyne, J. Appl. Cryst.,21, 645 (1988).The Berk and Hardman-Rhyne theory of beam broadening is reviewed and extended.
The relationship of the BH-R method to
earlier treatments of multiple scattering is described in detail.
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Characterization of Alumina Powder Using Multiple Small-Angle Neutron
Scattering. I. Theory
N. F. Berk and K. A. Hardman-Rhyne, J. Appl. Cryst.,18, 467 (1985).The theory of beam broadening is developed. The connection between dynamical scattering effects (primary extinction) and incoherent multiple scattering (secondary extinction) is established and the dependence of the theory on the phase shift parameter is developed.
The methodology of beam broadening analysis
described here and in the companion paper was subsequently refined by
Long and Krueger, who coined the acronym, MSANS
(MSAS). See G. G. Long and S. Krueger, J. Appl. Cryst., 22,
539 (1989).
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Characterization of Alumina Powder Using Multiple Small-Angle Neutron
Scattering. II. Experiment
K. A. Hardman-Rhyne and N. F. Berk, J. Appl. Cryst.,18, 473,(1985).The theory of beam broadening is applied to a green-state ceramic. The basic MSANS methodology of exploiting the wavelength dependence of multiple scattering was developed here.
NIST Center for Neutron Research
Last modified: May 18, 1998