Radiation Safety Manual Glossary - (P)

Particle Accelerator

any machine capable of accelerating electrons, protons, deuterons, or other charged particles in a vacuum and of discharging the resultant particulate or other radiation into a medium at energies usually in excess of 1 MeV. The National Superconducting Cyclotron Laboratory is a particle accelerator.

Photon

a quantum (or packet) of energy emitted in the form of electromagnetic radiation. Gamma rays and x-rays are examples of photons.

Pig

a container (usually lead or plastic) used to ship or store radioactive materials. The thick walls protect the person handling the container from radiation. Large containers are commonly called casks.

Pocket Dosimeter

a small ionization detection instrument that indicates radiation exposure directly. An auxiliary charging device is usually necessary.

Positron

particle equal in mass, but opposite in charge, to the electron; a positive charge.

Principal Investigator (P.I.)

a faculty member, assistant professor or higher (no visiting faculty), appointed by the licensee, who has been approved through the Radiation Safety Committee for the purchase and use of radioactive materials.

Protective Barriers

barriers of radiation absorbing material, such as lead, concrete, plaster and plastic, that are used to reduce radiation exposure.

Proton

an elementary nuclear particle with a positive electric charge located in the nucleus of an atom.

Public Dose

the dose received by a member of the public from exposure to radiation and to radioactive material released by a licensee, or to another source of radiation. It does not include occupational dose or doses received from background radiation, as a patient from medical practices, or from voluntary participation in medical research programs.