Calibration of Radium 226

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Calibration of Radium 226
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Introduction to Radium

• Discovered in 1898 by Marie Curie
• Radium (chemical symbol Ra) is a
  naturally-occurring radioactive metal. Its most
  common isotopes are radium-226, radium 224, and
  radium-228. Radium is a radionuclide formed by
  the decay of uranium and thorium in the
  environment. It occurs at low levels in virtually
  all rock, soil, water, plants, and animals.
• Early 1900s radium was used in such products as
  toothpaste, hair tonic, ointments, elixirs, glow
  in the dark watch faces, and was an early source
  of radiation treatment for cancer
• Now is it used in some industrial radiography
  devices and added to the tips of lightning rods,
  improving their effectiveness

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Ra226 Decay Chain
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Natural Radioactive Series
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Purpose

• To re-calibrate the radium-2 source and determine
  the correct energies for the alpha particles
  being emitted

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DOG Calibration

• Layer of dirt, oil, and grease on the radium 1
  source caused a downshift in energy

15 keV
18 keV
16 keV
10 keV
13 keV
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Ra-1 Shifted with Gold
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Ra-1 Spectrum with Am241 Peak
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Centroid vs. Edge Energies
4.784 MeV Ra234
7.687 MeV Po218
6.002 MeV Po220
5.489 MeV Rn226
5.304 MeV Po212
4.601 MeV Ra232
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5.304 MeV
4.784 MeV
6.002 MeV
7.687 MeV
5.489 MeV
4.601 MeV
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Centroid energies vs channel number
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Based on new calibration
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Re-Calibrated Radium 2 Source
New in blue old in red Blue 2006 calibration Red
1972 calibration
4.91 MeV
4.696 MeV
7.04 MeV
4.22 MeV
5.48 MeV
7.044 MeV
3.997 MeV
5.307 MeV
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• http//www.epa.gov/radiation/radionuclides/radium.
  htm
• http//www.physics.umd.edu/lecdem/honr228q/notes/U
  238scheme.gif
• http//www.eserc.stonybrook.edu/ProjectJava/Radiat
  ion/index.html