Understanding Neutron Radiography

Radioactive Sources
Many isotopic neutron sources make use of either the (α,n) or the (γ,n)
reaction for neutron production. These sources have been used for many
years for a variety of applications and they have the desirable features of
being reliable and at least semi-portable. However, the thermal-neutron
intensities that can be achieved from such isotopic source assemblies tend to
be low, especially when compared to an operating nuclear reactor.
Spontaneous fission of transplutonium elements is another neutronproducing
reaction that has received considerable interest for neutron radiographic
applications. Some pertinent data for several isotopic sources are tabulated in
Table 5.
Charlie Chong/ Fion Zhang