Chapter 28 Notes, part III

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Chapter 28 Notes, part III

• Fission, Fusion and Detecting Radiation

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Fission

• When bombarded with neutrons, some isotopes
  undergo fission.
• Rather than a or b decay, they break into two
  smaller atoms.

U-239
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Fission

• Fission can release enormous amounts of energy
  (hence the fission bomb).
• It can be controlled in two ways in order to
  allow the energy to be used productively.
  Through

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Fission

• Neutron moderationneutrons are slowed down in
  order to increase the speed of reaction
  (otherwise neutrons may be too fast). EX C or
  H2O
• Neutron absorptiondecreases number of neutrons
  to prevent reaction from going too fast. EX
  cadmium control rods

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Fission and the A-bomb

• The atom bomb was made by using plutonium (a
  radioisotope) as a source of neutrons with
  fissionable uranium, which released lots of
  energy.

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Fusion

• Fusion is when nuclei combine to form a nucleus
  of greater mass, which also releases huge amounts
  of energy.
• It requires extremely high temperatures to occur
  ( greater than 40 000 000oC)

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Fusion and the H-bomb

• The fusion bomb is hydrogen which is triggered
  into fusion with the reaction of a fission bomb.

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Detecting Radiation

• X-rays and radiation emitted by radioisotopes is
  called ionizing radiationradiation strong enough
  to knock an electron off of some atoms of a
  substance.

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Geiger Counter

• b radiation can be detected with a Geiger
  counter.
• It uses a metal tube filled with gas connected to
  an electric current meter. When ionizing
  radiation knocks off an electron, the resulting
  charge registers on the meter.

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Scintillation Counter

• A scintillation counter measures all ionizing
  radiation.
• The device uses a phosphor coated plate that when
  struck with radiation produces flashes of light.
  The number and energy of collisions is recorded.