Radioactive Isotopes

This seems simple enough, but making it work successfully has been developed over the decades, ever since radiation was discovered.

Geiger-Muller tubes are those famous microphone-like devices you see attached to boxes that click when reacting to radiation.  In movies and in the news, one can see them hard at work, being swept back and forth; clicking away as the suited users walk slowly through a "dangerous" area.  These radiation counters work by reacting to the gamma rays being given off by radioactive decay.  As each particle hits the tube, it gives off an electrical signal, which is detected by the box, and so gives off one click.

Liquid scintillation counters work much the same way, except it is light being detected instead of the particles of gamma rays.  The gamma rays play an important role, however, as they react with a substance called a Fluor, which gives off one photon as the gamma ray strikes it.

First, the laboratory personnel must make a "cocktail" of various substances besides the sample to be measured.  A mixture of radioactive liquid, such as tritium water, and a solvent, like benzene or toluene, is brought together along with the fluorescent substances used for light emission.  Then the sample is introduced into the cocktail, so that the radioactive isotope binds with it.

Fluorescent molecules are used in conjunction with the radioactive labeled sample, and as the beta particles, from gamma radiation, slam into the Fluors, a single photon is emitted.  Sensitive light sensors in the device can detect these elusive and faint particles, turning the light into a signal for the computer to calculate the quantifying enumerator.