The major radionuclides of concern are potassium, uranium, and thorium and their decay products.
Some of these decay products, like radium and radon, are intensely radioactive but occur in low concentrations.
In addition, the earth, and all living things on it, are constantly bombarded by radiation from outer space.
In these areas it can represent a significant health hazard.
Concentrations over 500 times higher than the world average have been found inside buildings in Scandinavia, the United States, Iran, and the Czech Republic.
A radiation detector is a device used to detect, track, or identify high- energy particles, such as those produced by nuclear decay, cosmic radiation, and reactions in a particle accelerator.
Modern detectors are also used as calorimeters to measure the energy of detected radiation.