Applications of Nuclear Physics

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Applications of Nuclear Physics

• Chp 43.5 43.7

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• Biological Effects of Radiation
• Applications to Astrophysics
• Nuclear Power

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Medical Applications of Nuclear Energy
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The Strange Tale of Alexander Litvenenko

• Former KGB agent and political whistle blower
  became suddenly ill on November 1, 2006 following
  a restaurant meeting with a Russian agent
• Died three weeks later. He is believed to be the
  first confirmed case of deliberate 210Po
  radiation poisoning
• It has been suggested that as little as 10 mg of
  Polonium was put in his tea this would be a
  fatal dose!

Alexander Litvenenko (1962-2006)
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The perfect assassin

• Po is readily available and essentially
  un-regulated in small amounts
• Po half-life is 138.4 d EK 5.41 MeV
• Is an alpha-emitter Easy to transport safely and
  lethal if ingested
• Does NOT emit gamma rays!
• Completely tasteless in quantities that would be
  lethal
• It is estimate that 1 g of Po introduced to an
  urban water supply could poison 20 million people
  with 10 million fatalities.

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Back of the envelope

• Assume it concentrates in the liver
• Calculate the radiation exposure this represents
• Ideas we need
• Units of radiation exposure
• Activity Bq
• Absorbed dose Gray Gy 1.00 J/kg (100 rad)
• Relative biological effectiveness RBE
• REM rad X RBE
• Dose equivalent absorbed dose X RBE in Sieverts
  Sv (an older unit is the REM 0.010 Sv)

Dose (REM) Effect
gt 1000 Death in a few days
100 - 1000 Death in a few weeks
50 High probability of cancer in next 30 years
Type RBE
a 10-20
b 1-2
g 1
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Older terms

• The Roentgen amount of ionizing radiation
  producing 0.3 nC in 1 cc of air
• 1 rad amount of radiation which would deposit
  0.01J/kg in any material
• SI unit is the GRAY 100 rad
• When considering biological effects the REM is
  often used rad X RBE

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Fukushima

• Major radio nuclides being released are 137Cs
  (t1/2 30 a) and 131I (t1/2 8 d)
• A core breach exposes fuel rods
• Iodine concentrates in thyroid, Cs concentrates
  in muscle throughout body

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Positron Emission Tomography

• fluorodeoxyglucose (FDG), C6H11FO5 is a sugar
  that is commonly used in nuclear medicine
• The fluorine atom is labeled instead of
  normal F, it is
• This decays via a b process write the equation
  for this and predict the final product
• The positron emitted doesnt get far!

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Conservation Laws make this all possible!
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Stellar Structure and Evolution

• Hydrogen fusion in Solar Mass stars the
  proton-proton cycle
• 4 1H ? 4He
• CNO cycle in higher mass stars
• (link to astronomy notes)

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Back of the envelope

• Sun emits 3.99 x 1026 J/s
• PP-chain fusion reaction releases about 25 MeV
• Solar Mass is 1.99 x 1030 kg
• From this we can estimate the life expectancy of
  the Sun!

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Supernovae and Nucleosynthesis

• Recall the binding energy curve

(link to astronomy notes)
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• Questions to work on
• You are 1m from a 1 kg lump of pure radium!
• What kind of radiation are you likely going to be
  exposed to?
• Estimate the exposure you will receive in REM
  over 1 hour
• What is your prognosis?