Editorial

Abstract

The history of neutron scattering dates back to the early 1950s when the first research reactors were built. Thanks to their unique properties, neutrons have been used to investigate an ever-growing number of materials in practically all disciplines of the natural sciences. Now a third generation of neutron sources is emerging: Spallation sources are in operation in the USA, under construction in Japan, and in the planning stage in Europe. Spallation sources offer an unprecedented jump of some two orders of magnitude in the crucial performance parameter, the instantaneous peak flux, compared to the leading neutron sources of today. It is the dedicated goal of these new projects to combine the vastly enhanced, unique source quality with the most advanced instrumentation concepts. However, the existing lists of instruments to be installed at the new sources hardly reveal truly innovative concepts: Diffractometers and chopper spectrometers have already been used by pioneers like Shull and Brockhouse fifty years ago; small-angle scattering (including reflectometry) and back-scattering techniques as well as interferometry and polarized neutrons were introduced in the sixties; and the neutron spin-echo technique was invented by Mezei more than thirty years ago. In contrast, complementary methods like synchrotron x-ray and magnetic resonance experiments have seen permanent efforts to create rich inventories of different techniques, and these developments are being continued in a persistent manner. This is the reason why synchrotron x-ray techniques carry the labels “innovative” and “highly appealing,” whereas the label “old technique” sticks to neutron scattering, as was strikingly commented by Joël Mesot in his recent editorial in Neutron News [1].