What is Radiation?

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What is Radiation?

• Health Physics Society - Power Reactor Section
• Radiation Science Education

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Outline

• Ionizing Non-Ionizing
• Photons Particles
• Stable Unstable Atoms
• Half -Life
• Radiation Detectors

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Ionizing Non-Ionizing Radiation

• Ionizing Radiation Radiation is energy
  transmitted as particles or waves. Ionizing
  radiation has sufficient energy to dislodge
  orbital electrons, thereby producing ions.
• Examples alpha, beta, gamma, neutron, and
  x-rays
• Non-Ionizing Radiation Radiation that does not
  have sufficient energy to dislodge orbital
  electrons.
• Examples visible light, infra-red ,
  micro-waves, radio-waves, and radar

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Ionizing Radiation Hits An Atom
Ejected Electron
Incoming Photon
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Particles and Photons

• Radiation can be in the form of particles or
  waves (photons).
• The most common types of ionizing radiation are
  alpha, beta, gamma, neutron, and x-rays.
• Gamma and x-ray radiation are photons. They are
  part of the electromagnetic spectrum and
  considered packets of pure energy.
• Alpha, beta, and neutron radiation are particles
  having mass. Betas are electrons and alphas are
  helium nuclei.

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Electromagnetic Spectrum
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Radioactive Decay The process of unstable
atoms spontaneously emitting radiation.
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Half-Life 1.3 billion years
Parent Nucleus Potassium-40 Unstable atom
Daughter Nucleus Calcium-40 Stable atom
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What is Half-Life?

• Radioactive decay is the process where an
  unstable atom emits radiation.
• Radioactive decay changes unstable atoms into
  more stable atoms.
• Half-life is the time it takes for 1/2 the atoms
  of a particular radioactive element to transform
  itself by decay.

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Gas-Filled Detectors
Voltage Source
Incident Ionizing Radiation



Electrical Current Measuring Device
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Anode
Cathode -
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Key Concepts

• Radioactive Decay The process where an unstable
  atom transforms itself into a more stable atom by
  spontaneous emission of radiation.
• Ionizing Radiation Any radiation which is
  capable of dislodging electrons from atoms
  thereby producing ions.
• Half Life The time it takes for one-half of the
  atoms of a particular radioactive element to
  transform itself by radioactive decay.

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References

• Nuclear Regulatory Commission Home Page
  www.nrc.gov
• teachers corner_at_www.nrc.gov/NRC/teachers.html
• students corner_at_www.nrc.gov/NRC/STUDENTS/students.
  html
• Nuclear Energy Institute Home Page www.nei.org
• science club_at_ www.nei.org/scienceclub/index.html
• Health Physics Society Home Page www.hps.org
• www.hps.org/publicinformation/radfactsheets/