• Radiation - Radiation is energy in the form of waves or particles given off during radioactive decay, or as a consequence of certain physical processes that we can control. Examples of these are x-ray machines and particle accelerators.
  • Wave radiations include gamma and x-rays. A common term used to describe this type of radiation is photon radiation.
    
    
  • Particle radiation can consist of charged or uncharged particles which are emitted with very high velocity.
    
    

    Radiation travels from its source at very high speed, and depending on the type, may be able to penetrate easily through very dense materials.

• Radioactive material - Any material that contains radioactive (unstable) atoms. Radioactive materials are everywhere. Usually, we only encounter them in very small amounts. Since radioactive material contains unstable atoms, it emits radiat ion.

• Radioactive contamination - Not all radioactive material is considered "contamination". contamination is radioactive material that is in a form or location which may allow it to be spread to unwanted locations. Many radioactive sources are s ealed or are in a form that isolates the material from potential spread. Contamination may be Fixed, Transferable (loose), or Airborne.

It is important to note that exposure to radiation does not result in contamination of the worker. You may become contaminated only through direct contact with material that has removable radioactive material, or by working in areas where this contaminated material is handled.

• Radioactivity - Radioactivity is the process od unstable (or radioactive) atoms becoming stable by emitting radiation. The radioactive decay process involves fundamental physical constants which enable us to characterize and measure radioacti ve materials very accurately.
  
  
• Radioactive half-life - Radioactive half-life is the time is takes for one half of the radioactive atoms present in a given sample to decay. The half-life of a particular isotope is a constant, and depending on the isotope it may range from a fraction of a second to millions of years. After seven half-lives the activity will be less than 1% of the original activity.

Ionization - The process of ionization is important in understanding radiation, because it is this process that differentiates ionizing radiation from other types. Ionization is the process of removing electrons from atoms. If enough energy is supplied to remove electrons from the atom the remaining atom has a + charge. The positive charges atom and the negatively charges electron are called an ion pair. Ionization should not be confused with radiation. Ions (or ion pairs) can be the result of radiation exposure and allow the detection of radiation.

Typically, we classify types of radiation as ionizing or non -ionizing radiations depending on whether or not the radiation can form ion pairs in common material such as air ot tissue.

• Ionizing radiation - Radiation which has enough energy to ionize an atom is called ionizing radiation. The four basic types of ionizing radiation that are of primary concern to us are alpha particles, beta particles, gamma rays (includes x -rays) and neutron particles.
  
  
• Non-ionizing radiation - Radiation that doesn't have the amount of energy needed to ionize an atom. Examples of non-ionizing radiation are ultraviolet rays, microwaves and visible light.

Review:

Ionizing radiation may be defines as 1) in the form of 2) or 3) which has sufficient energy to 4) matter.

Unstable atoms which give off radiation when they decay are known as 5) material.

Radioactive material on surfaces or in liquids, which might be easily transferred to surfaces or personnel is known as 6).

Ionization is the process of removing 7) from 8).

After two half-lives, what percent of the original radioactive material will remain? 9).

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