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![[Figure 2]](in5071fig2mag.jpg)
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Figure 2
A sketch of the neutron scattering geometry. The applied magnetic field B0 ∥ ez is perpendicular to the wavevector k0 ∥ ex of the incident neutron beam (B0 ⊥ k0). The momentum transfer or scattering vector q is defined as the difference between k0 and k1, i.e. q = k0 − k1. SANS is usually implemented as elastic scattering (k0 = k1 = 2π/λ) and the component of q along the incident neutron beam, here qx, is much smaller than the other two components, so that ![[{\bf q} \cong [0, q_{y}, q_{z}] = q[0, \sin\theta, \cos\theta]]](teximages/in5071fi46.svg) . This demonstrates that SANS predominantly probes correlations in the plane perpendicular to the incident beam. For elastic scattering, the magnitude of q is given by ![[q = (4\pi/\lambda) \sin(\psi)]](teximages/in5071fi47.svg) , where λ denotes the mean wavelength of the neutrons and 2ψ is the scattering angle. The angle θ = ∠(q, B0) is used to describe the angular anisotropy of the recorded scattering pattern on the two-dimensional position-sensitive detector. |
![[Figure 2]](in5071fig2.jpg)
 | JOURNAL OF APPLIED CRYSTALLOGRAPHY |
ISSN: 1600-5767
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