ABSTRACT
Two of the three main sources of neutron emissions within the solar system – cosmic ray interactions and natural radioactivity (neutron activation analysis is described in Chapter 7) – are discussed. The detection of neutrons through their absorption by a suitable nucleus followed by the radioactive decay of that nucleus and the detection of its high–energy decay products or by elastic scattering reactions leading to a high energy ion that may in turn be detected is then covered. A brief mention is also made of calorimeter-based detectors. The usage and practical design of each detector type is illustrated by example instruments from past, present and future spacecraft missions.
