The use of multiple-scattering data to enhance small-angle neutron scattering experiments

Abstract

Multiple scattering of neutrons by the inhomogeneities responsible for small-angle neutron scattering (SANS) during the passage of the beam through the specimen can be used to provide valuable information about the shape of the objects and the absolute value of the contrast between the scattering particles and the matrix. The neutrons emerging from the specimen are classified into those that have been scattered n times. The index n ranges from zero to infinity. The remnant of the incident beam is the group of neutrons for which n equals zero. Each group contributes separately to the scattering profile. The small-angle scattering cross section is independent of the neutron wavelength for n = 1 only. Thus collection of data as a function of specimen thickness and of neutron wavelength will provide a number of different profiles describing the same physical situation. Simultaneous analysis of these profiles provides absolute values of the cross section for scattering into the small-angle region and of the cross section for removal of neutrons from the small-angle region. So that the method can be used generally, a profile function that is a very good approximation to those in the literature is introduced. The implications for time-of-flight SANS are discussed.

Small angle neutron scattering study of pore microstructure in ceria compacts

“…A porous sintered sample can be considered as two-phase system consisting of pore space and material medium. SANS profiles have been modelled by applying fractal concept and are fitted with modified Debye-Bueche function [10], given by the expression…”

Behavior of cold-worked AISI-304 steel in stress-corrosion cracking process: Microstructural aspects

“…copper precipitates in a iron matrix which can have different shapes and sizes (spherical, ellipsoidal, etc.) where the scattering pattern will be different [8]. Moreover, if the concentration of this type of inhomogeneities is high enough they can interact with each other.…”

Neutron Tomography

“…The broadening B (t) [nm -1 ] of a scattering function due to (ultra) small-angle scattering (t again means the scanning parameter defined in Eq. [6.4]) can be (roughly) approximated by a Gaussian distribution and, involving multiple scattering, written as [24,25] where ' is the scattering cross section, N(x,y) is the particle density distribution, and R is a parameter with the dimension of a length specifying an average size or correlation length in the scattering object (corresponding to the Gaussian approximation). Now one can use B or B 2 as an imaging signal to use (ultra) With this proper description of P (t) ¼ B 2 (,t), the standard methods of reconstruction such as the FBP can be used.…”