A gamma spectrum
A consequence of the nuclear energy levels is the emission of gamma photons with characteristic energies. These rays play the part of digital fingerprints, frequently used to identify radioactive nuclei in a given sample. The image above shows the photons coming out of such a sample, and the precisely measured energies associated with each. We can quickly see a series of characteristic lines, indicating the existence of certain elements. The continuous background measurements, which exceed the 100 kiloelectronvolts that is the maximum energy X rays can have, are caused by the presence of poorly detected gamma rays.
IN2P3