Chapter 1 gives a theoretical background, while Chapter 3 deals with the practical implementations. Thus, these chapters provide the background to determine what one can expect from the experiments. The remainder of the book is devoted to the practical instrumentation of the experiments. Each chapter deals with specific types of instruments and devices, discusses briefly the electronics involved, considers the limitations, and investigates how and to what extent they can be circumvented. The advantage of having different contributors, each with his own practical experience, shows clearly in this latter aspect. Detailed practical knowledge and experience can be explained best by the person who has long been con­ cerned with the subject theoretically and practically.