Abstract and subjects
The neutrons and gamma rays emitted after fission have been intensely studied ever since its discovery. The excited fragments return to their ground states via prompt neutron and gamma emission. While most of the fragment excitation energy is removed by neutron emission, gamma emission returns the product nucleus to its ground state. Delayed emission occurs at longer time scales and contributes only a small fraction of the total neutron and gamma emission. The general characteristics of neutron and gamma emission are described in Sect. 3.1 without reference to models. An overview of experimental techniques is presented in Sect. 3.2. Section 3.3 describes the nuclear physics pertinent to neutron and gamma emission. It then discusses fission models, starting from parameterizations of the neutron spectrum to deterministic models and, more recently, complete event fission models. One of the notable advances enabled by complete event fission models of fission is the study of more complex correlations between the fission fragments, the neutrons and gamma rays. This advance has encouraged detailed measurements of correlations, including between neutrons and gammas. Finally, delayed neutron and gamma emission is briefly discussed in Sect. 3.4.