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Basic neutron scattering next up previous
Next: Basic understanding of instrument Up: McStas neutron ray-trace tutorial Previous: Goals and tasks

Basic neutron scattering

You may recall the Bragg law from your high school physics


giving the scattering condition for a wave of wavelength $\lambda$ against a series of lattice planes with lattice spacing $d$, rotated the angle $\theta$ off the lattice plane normal. $n$ is an integer giving the spectral order of the scattered wave. In neutron science one often refers to the scattering vector, $\vec{\kappa}$ of a given reflection, where


This gives us the scattering vector formulation of the Bragg law


where $k=\frac{2\pi}{\lambda}$. The Bragg law / scattering condition is illustrated in Figure 1.
Figure 1: Illustration of the Bragg Law.
Most of the neutron processes we will study in this paper are elastic, meaning that the wavelength of the neutron is unaltered by the process.

Peter Kjær Willendrup 2015-11-12

Last Modified: Thursday, 12-Nov-2015 11:53:11 CET
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