Introduction

Background

Neutron scattering had its origin in 1932, the year that marked the discovery of the neutron by Chadwick, and the first nuclear reactors were successfully operated in Chicago and Oak Ridge in the early 1940s. It is there that the technique of neutron scattering can be said to have begun and, during its initial stages, it was used mainly for the study of “hard” crystalline materials. For example, the pioneering research of C. G. Shull, E. O. Wollan, and B. N. Brockhouse, which led to the 1997 Nobel Prize for Physics, began with studies of materials such as iron, chromium, cobalt, and iridium, and was followed by the development of polarization analysis [1] to determine the structure of magnetic materials. Such studies continue to give important structural information [2], though, during the last two decades, the technique has been used increasingly by scientists from other disciplines (polymer science, chemistry, biology). Thus, many of these more recent applications have involved “soft” matter such as polymers [3] and colloids [4], which have become some of the most practical and widely used materials today. This development may be seen as part of an even broader trend within the sciences, as noted by P. G. de Gennes [5]: