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    The elements that make up all matter are composed of atoms. Each atom is made up of three major parts that help form the atom's physical and chemical properties. The three basic particles are:

    1. Proton - positive charge, in the nucleus.

    2. Neutron - neutral (no) charge, in the nucleus.

    3. Electron - negative charge, orbits the nucleus.

    Atoms may be referred to as stable or unstable.

    Radiation (or ionizing radiation) is energy in the form of waves (rays) or particles which can penetrates matter and cause ionization.

    Radioactive Material is any material which contains unstable atoms that emit radiation.

    Radioactive material may exist in any physical form, such as solids or liquids. Any radioactive material which is in a form that is easily spread or has been transferred to surfaces, liquids, or the atmosphere is known as radioactive contamination. Contamination is a concern due to the potential for its spread to personnel.

    A simple definition for Radioactive Contamination:

    Radioactive material in an unwanted place.

    Radiation may be emitted from sources other than radioactive materials. Certain physical processes (such as those used in x-ray machines) may cause the production of ionizing radiation. The operation of the electron accelerator at CEBAF involves such processes. Due to the high energy nature of CEBAF's beam, it can also cause the formation of radioactive material. This material is produced in and among the components of the accelerator.

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