What are Radioisotopes?
Radioisotopes are radioactive forms of elements that have the same number of protons but a different number of neutrons, for example hydrogen-3. The unstable make-up of these isotopes causes them to undergo radioactive decay, characterized by the half-life of the specific isotope species. The detection of radioisotopes is due to their emission of gamma rays or subatomic particles as they undergo this radioactive decay, allowing their presence to be detected and quantified. Similar to stable isotopes, radioisotopes can be used to trace the movement of elements through natural systems, as well as to quantify the rates of natural processes, and the fate of contaminating sources. For example, tritium (hydrogen-3) radioisotope analysis is often used for studying the age, the source, and the recharge capabilities of groundwater aquifers necessary for providing fresh drinking water.
How do Scientists Measure Radioisotopes?
Liquid scintillation counting (LSC) is the most widely used technique for the detection and quantification of the particles emitted during radioactive decay. Sample material is immersed in a scintillation cocktail that becomes excited, and releases light photons that can be measured. The intensity of the light, and the number of photons released is directly proportional to the initial energy of the emitted beta particle. Radioactivity is measured in counts per minute (CPM), and is used to calculate the activity of the radioisotope.