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Chapter 3
Sources of 14 MeV Neutrons
3.1 INTRODUCTION
In 1920, Rutherford postulated that there were neutral, massive particles in the
nucleus of atoms. James Chadwick, a colleague of Rutherford, discovered the
neutron in 1932. He bombarded a beryllium target with alpha particles produc-
ing neutrons that recoiled into a block of paran. Chadwick’s apparatus, the
rst neutron generator (NG), is schematically described in Figure 3.1.
By measuring protons emerging from the paran with a Geiger counter,
Chadwick inferred that the neutron had a mass comparable to that of the pro-
ton. Soon Enrico Fermi recognized that neutrons could be used to produce ...