This interdisciplinary field draws on experimental and theoretical nuclear and medical physics.
Radioactivity is an amount of a radionuclide in a particular energy state at a given time.
Mathematically, it is defined as the quotient of d N by d t , where d N is the number of spontaneous nuclear transformations from that energy state in the time interval d t . The half life is the time necessary for one half of the nuclei to decay. Beta particles are high-energy electrons emitted by the nucleus in nuclei that contain too many or too few neutrons. For a system with excess neutrons, the neutron is transformed into a proton and in the process an electron and an antineutrino are emitted. The emitted negatively charged beta particles, usually denoted as - , have a continuum of energies from zero to a maximum energy denoted by E max .