4. Neutrons

4.1 Introduction

Neutrons arise from spontaneous fissions of heavy transuranic nuclei. The best-known neutron source is ²⁵² Cf, which emits 2.3 × 10 ⁶ n/(s · µg) and has a half-life of 2.65 years. The emission spectrum is a Maxwell distribution between 0 and 10 MeV, with an average energy of around 2 MeV.

One method of generating neutrons, in addition to induced fission, is to cause a nuclear reaction in certain light nuclei such as beryllium using α particles: