Types of RadiationWritten by: Harry VanWagenen
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  • Radiation is a process in which energetic particles or energetic waves travel through vacuum, or through matter-containing media that are not required for their propagation.
  • Radiation is energy that comes from a source and travels through space and is able to penetrate various materials.
  • Radiation is emitted by atoms with unstable nuclei. These atoms give off the excess energy or mass

The three main types of ionizing radiation and their symbols
The three main types of ionizing radiation and their symbols
The main types of radiation and their penetrating distances
The main types of radiation and their penetrating distances

Ionizing Radiation
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Ionization is the process in which a charged portion of a molecule, usually an electron, is given enough energy to break away from the atom. Ionization results in the formation of two charged particles or ions: the molecule with a net positive charge and the free electron with a negative charge. A free electron is an electron that is not attached to an atom or ion or molecule but is free to move under the influence of an electric field. Each ionization releases about 33 electron volts. Material surrounding the atom absorbs the energy. Ionizing radiation deposits a large amount amount of energy into a small area. All ionizing radiation is capable, directly or indirectly, or removing electrons from most molecules. The 33 eV from one ionization is disrupt the chemical bond between two carbon atoms.

Alpha Radiation

Alpha radiation is a heavy, short range particle and is an ejected helium nucleus.
  • fast moving helium atoms
  • high energy- in the MeV range
  • they can be stopped by a few inches of air or a piece of paper due to their large mass
  • most alpha radiation does not penetrate human skin or clothing
  • alpha-emitting materials are only harmful to humans if they are inhaled, swallowed, or absorbed through open wounds
  • alpha radiation is detected by a thin-window Geiger-Mueller probe
  • not an external hazard

Beta Radiation

Beta radiation is a light, short range particles and is an ejected electron.
  • fast moving electrons
  • energy ranges from a few 100 keV to several MeV
  • since electrons are lighter than helium atoms, they can penetrate father
  • beta radiation can travel several feet in the air
  • beta radiation can penetrate human skin to the germinal layer where skin cells are produced
  • if beta-emitting contaminants remain on the skin for a long time, they can cause injury
  • beta-emitting contaminants are harmful if deposited internally.
  • a thin-window GM probe can detect beta radiation
  • clothing provides some radiation against beta radiation

Gamma Radiation

Gamma radiation is a highly penetrating electromagnetic radiation.
  • originate from the nucleus
  • photons with a higher energy than light
  • energy ranges from several keV to serveral MeV
  • depending on their energy, gamma rays can be stopped by a sheet of aluminum foil or can penetrate several inches of lead
  • travel many feet in the air and many inches in human tissue
  • penetrate many materials and are called "penetrating radiation"
  • clothing provides little shielding from gamma radiation but will prevent contamination of the skin from gamma-emitting materials
  • easily detected by survey meters with a sodium iodide detector probe
  • external hazard to humans

X-ray Radiation

X-ray radiation is a highly penetrating electromagnetic radiation.
  • originate from the electron shell
  • photons with a higher energy than light
  • energy ranges from 10 keV and a few hundred keV
  • X-ray machines using x-rays to take advantage of the absorption between difference between bone and soft tissue which allows physicians to determine the structure of the human body
  • x-ray can penetrate the human skin and several inches of lead
  • lead sheilds and aprons are used to prevent the penetration of x-ray radiation
  • external hazard to humans

Neutron Radiation

Neutron radiation is an ionizing radiation that is found in nuclear reactors and bombs.
  • only ionizing radiation that can make objects or materials radioactive
  • when humans are exposed to too much neutron radiation, they skin becomes radioactive and they die
  • neutron radiation is released by a neutron bomb which kills people and animals but leave structures intact
  • neutron radiation can be blocked by concrete
  • neutrons are categorized by their speed
  • high-speed neutrons have the ability to directly ionize atoms

Gamma Radiation VS X-ray Radiation

  • the difference between gamma and x-ray radiation is how they are produced
  • gamma radiation originates from the nucleus
  • x-ray radiation originates from the electron shell
  • both radiations are external hazards to humans
  • both are electromagnetic radiations
  • both accompany the emission of alpha and beta radiation during radioactive decay
  • both are penetrating radiations

* Here is a quick video on the 3 main types of ionizing radiation: http://www.youtube.com/watch?v=vuGvQjCOdr0

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Non-Ionizing radiation ranges from extremely low frequency radiation into the ultraviolet range. Extremely low frequency radiation has very long wave lengths, 1 million meters or more, and frequencies 100 Hertz. Radio frequencies have wave lengths between 1 and 100 meters and frequencies in range of 1 million to 100 million Hertz. Microwaves have wave lengths that are about 1 hundredth of a meter long and frequencies of about 2.5 billion Hertz.

The non-ionizing portion of electromagnetic radiation consists of electromagnetic waves, that are not energetic enough to detach electrons from atoms or molecules. These include radio waves, microwaves, infrared, and visible light. The occurrence of ionization depends on the energy of the individual particles or waves. An intense flood of particles or waves will not cause ionization if these particles or waves do not carry enough energy to be ionized, unless they raise the temperature of a body to a point high enough to ionize small fractions of atoms or molecules by the process of thermal-ionization.

The Electromagnetic Spectrum

The electromagnetic spectrum is the range of all possible electromagnetic radiation frequencies. The electromagnetic spectrum is the characteristic distribution of electromagnetic radiation emitted by, or absorbed by, that particular object. All electromagnetic waves travel at the speed of light.

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Visible Light

  • also known as light
  • very narrow range of electromagnetic radiation of a wavelength that is visible to the human eye
  • the only part of the electromagnetic spectrum that we can see


  • wavelengths are than that of visible light but are shorter than the wavelengths of microwaves
  • humans feels infrared radiation though the sun's heat
  • remote controls use infrared to change the channel
  • lies between the visible and invisible portion of the electromagnetic spectrum


  • invisible
  • heats up food quickly
  • microwaves are used for transmitting information since they can travel through haze, clouds, or smoke


  • type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum
  • naturally occurring radio waves are made by lightning and astronomical objects
  • artificially generated radio waves are used for radio communication, broadcasting, radar, and for navigation
  • Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere
    -long waves may cover a part of the Earth very consistently
    -shorter waves can reflect off the ionosphere and travel around the world
    -much shorter wavelengths bend or reflect very little and travel on a line of sight.


  • UV rays are why humans become sunburned
  • humans cannot see UV rays but some insects can
  • the atmosphere's ozone layer blocks most UV rays
  • since the ozone layer is deteriorating, UV levels are increasing
  • UV rays can cause skin cancer

Visible Light
Visible Light
Microwave radiation
Microwave radiation
Ultra Violet
Ultra Violet

Works Cited