Nuclear Science: ALARA (As Low As Reasonably Achievable): ALARA is a radiation safety principle for minimizing radiation doses. It is a regulatory requirement for every radiation safety program.

Alpha Particle: an alpha particle is a highly ionizing form of particle radiation that has low penetration. It is made of two neutrons and two protons bound together into a particle that is identical to helium.

Atom: an atom has protons and neutrons in the nucleus which is in the center of the atom, and the electrons circle the nucleus. The protons and the neutrons are aproximately 1800 times larger than the electrons, but the neutron is a little larger than the proton.

Beta Particle: Beta particles are high-energy, high-speed electrons. The beta particles emmitted are a form of ionizing radiation also known as beta rays.

Background Radiation: Background radiation is the ionizing radiation emitted from a variety of natural and artificial radiation sources.

Contamination: Radioactive contamination is the uncontrolled distribution of radioactive material in a given environment. The amount of radioactive material released in an accident is called the source term.

Curie: The curie (symbol Ci) is a unit of radioactivity, defined as 1 Ci = 3.7×1010 decays per second. This is roughly the activity of 1 gram of the radium isotope 226Ra, a substance studied by the pioneers of radiology, Marie and Pierre Curie (for whom the unit is named). The curie has since been replaced by an SI derived unit, the becquerel (Bq), which equates to one decay per second. Therefore: 1 Ci = 3.7×1010 Bq and 1 Bq = 2.70×10−11 Ci

 Becquerel:The becquerel (symbol Bq) is the SI derived unit of radioactivity, defined as the activity of a quantity of radioactive material in which one nucleus decays per second. It is therefore equivalent to s-1. The older unit of radioactivity was the curie (Ci), defined as 3.7×1010 becquerels or 37 GBq. The becquerel is named for Henri Becquerel, who shared a Nobel Prize with Pierre and Marie Curie for their work in discovering radioactivity.In a fixed mass of radioactive material, the number of becquerels changes with time. Sometimes, amounts of radioactive material are given after adjustment for some period of time. For example, one might quote a ten-day adjusted figure, that is, the amount of radioactivity that will still be present after ten days. This de-emphasizes short-lived isotopes. SI uses the becquerel rather than the second for the unit of activity measure to avoid dangerous mistakes: Becquerels are proportional to more active, and thus more dangerous sources of radiation, while seconds are inversely proportional.

Gamma Ray: Gamma rays or gamma-ray photons (denoted as γ) are forms of electromagnetic radiation (EMR) or light emissions of a specific frequency produced from sub-atomic particle interaction, such as electron-positron annihilation and radioactive decay; most are generated from nuclear reactions occurring within the interstellar medium of space. Half Life: The half-life of a quantity subject to exponential decay is the time required for the quantity to decay to half of its initial value. The concept originated in the study of radioactive decay, but applies to many other fields as well, including phenomena which are described by non-exponential decays. Ionization: Ionization is the physical process of converting an atom or molecule into an ion by changing the difference between the number of protons and electrons. This process works slightly differently depending on whether an ion with a positive or a negative electric charge is being produced. A positive electric charge is produced when an electron bound to an atom or molecule absorbs enough energy from an external source to escape from the electric potential barrier that originally confined it. The amount of energy required being equal to the Ionization potential. A negative electric charge is produced when a free electron collides with an atom and is subsequently caught inside the electric potential barrier, releasing any excess energy. Quark: In particle physics, quarks are one of the two basic constituents of matter (the other are the leptons). Quarks are the only fundamental particles that interact through all four of the fundamental forces. The word was borrowed by Murray Gell-Mann from the book Finnegans Wake by James Joyce, where seabirds give "three quarks", akin to three cheers (probably onomatopoetically imitating a seabird call, like "quack" for ducks). Isotope: Isotopes are any of the several different forms of an element each having different atomic mass (mass number). Isotopes of an element have nuclei with the same number of protons (the same atomic number) but different numbers of neutrons. Therefore, isotopes have different mass numbers, which give the total number of nucleons—the number of protons plus neutrons. Neutron: In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939.573 MeV/c² (1.6749 × 10-27 kg, slightly more than a proton). Its spin is ½. Its antiparticle is called the antineutron. The neutron, along with the proton, is a nucleon.