A series of nuclear transmutations occurs until a stable nucleus results. Gamma decay is the release of excess stored energy from the nucleus. No transmutation occurs. However, gamma decay often accompanies alpha and beta negative decay in a disintegration series. Nuclide charts , with atomic number plotted against neutron number, are used in nuclear physics to illustrate a disintegration series.
Background radiation comes from a variety of radioactive sources.
Each radioactive nuclide emits radioactivity at its characteristic rate, different from that of other nuclides. The rate of radioactive decay is related to the energy change that accompanies the transformation, but it is not a direct relationship. The rate of radioactive emissions of a radioactive nuclide is directly proportional to the amount of radioactive material present. The decay constant is a measure of the rate at which the nuclide releases radioactive emissions. The mean, or average lifetime of a nuclide, .