Page 67 - Neutrons for Sciences and Society

Chapter 3 - Why invest so much money in a source of neutrons?
life sciences has not had the development which might have been expected. This is mainly due to the outstanding quality of data that can be collected with X-rays thanks to powerful modern sources such as synchrotron radiation, which can locate hydrogen in simple molecules. There are, though, cases where hydrogen plays an important role in catalytic processes induced by proteins where neutron diffraction provides more detailed information (see, for example, work on endothiopepsin54).
3.2.2 Small Angle Scattering
These studies have expanded considerably. With this technique one does not attempt to determine structures at an atomic scale, but rather shapes and sizes of a microscopic object. There are many applications in both pure and applied research for studying polymers, colloids, alloys (grain structure), superconductors, and viruses. Here too the main assets are the neutron sensitivity to hydrogen and magnetism as well as their ability to penetrate thick samples.
3.2.3 Inelastic Scattering
The change of neutron energy is measured after impact with atoms in motion. As just mentioned, when the sample is a crystal these movements are quantised and are described in terms of phonons. The wave motion modes have characteristic energies
54 L. Coates, P.T. Erskine, S.P. Wood, D.A.A. Myles, J.B. Cooper, Biochemistry, (2001), 40, 13149-13157, DOI 10.1021/bi010626h
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