Measurement of Nuclear Radiation and Radioactivity

In this chapter we will focus on nuclear radiation as a tool for measuring radionuclides in environmental samples. For example, we might determine the activity of214Pb in a compacted filter by counting the 352-keV gamma rays emitted during decay of214Pb, or the activity of239Pu collected on the surface of a filter by measurement of its 5.16-MeV alpha particles. As pointed out in Chapt. 2, with radioactive substances it is usually easier to measure the nuclear radiation (alpha particles, beta particles, gamma rays, etc.) emitted by the radioactive atoms than to measure the radioactive atoms themselves. It can be difficult to separate the radioactive atoms from stable atoms, and the collective mass of the radioactive atoms is usually too small to measure directly. However, there are some exceptions as will be mentioned below.