Chapter 1: Introduction

Writing this book started almost exactly 50 years after neutrons with velocities of ≈5m/s and below had first been observed. In early February 1968, a doctoral student (A.S.) working under the supervision of Heinz Maier-Leibnitz at the Research Reactor facility FRM of the Technical University of Munich at Garching, was, after two years of preparation, finally ready for first measurements at a neutron guide tube which selected extremely slow neutrons from the thermal neutron spectrum of the Reactor. To slow the neutrons further down, the guide tube was installed vertically inside the water pool of the Reactor to force the neutrons into motion upward against gravity. On their way up, the neutrons lost the last bit of kinetic energy and arrived at the detector with almost none left. In fact, some neutrons must have failed to climb all the way up to the detector since their energy had been insufficient for the full vertical climb. The significance of these first measurements was the recording of a spectrum of neutrons with energies spanning the range from about 200m/s all the way down to less than 5m/s (the speed of a leisurely bike ride)…