Energy Loss and Penetration of Radiation through Matter

For the discussion that follows, ionizing radiation is divided into three groups:

1. Charged particles: electrons (e−), positrons (e+), protons (p), deuterons (d), alphas (α), heavy ions (A > 4)

2. Photons: gammas (γ) or x-rays 3. Neutrons (n)

e division into three groups is convenient because each group has its own characteristic properties and can be studied separately.