Radiation Protection Glossary

A radiation protection glossary for Radiation Protection Supervisors (RPS), Radiation Protection Advisers (RPA) and anyone else interesting in radiation safety terms and definitions. The glossary is a mixture of health physics , phrases related to radiation protection legislation, transport, practical safety, technical terms and similar.

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For formal advice, see our Radiation Protection Adviser pages. 



    The neutrino is a particle with no mass or charge. It is emitted during Beta decay during the emission of a beta particle. It has no great significance with respect to Radiation Protection but great interest still remains in its properties.


    The neutron is a constituent of the Nucleus of an Atom and has an Atomic Mass unit of 1 (identical mass to a Proton). Unlike protons, the neutron does not carry an electrical charge. Its electrical neutrality allows it to take part in many types of nuclear reactions because it is not deflected by the positive charge of the protons. Neutrons are not themselves Ionising, but the by-products of their interactions are (in simple terms their interactions take the form of collisions with other sub-atomic particles where energy is transferred).

    Non-Ionising Radiation

    Non-ionising radiation dose not have the ability to Ionise matter it interacts with. Examples include radio waves and microwaves. Non-ionising radiation is not considered in the Ionising Radiations Regulations 2017 (IRR17).


    The nucleus contains positively charged Protons and uncharged Neutrons which are bound by nuclear forces. The nucleus makes up the central portion of an Atom and is surrounded by orbiting Electrons. (This description is much simplified but serves its purposes for most practical Radiation Protection purposes).


    A nuclide describes an Atom who's properties are a function of the number of Protons and Neutrons contained in the Nucleus. A nuclide does not have to be Radioactive - if it is, then its known as a Radionuclide.

Imagination is more important than knowledge

– Albert Einstein -