Nuclear Radiation

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Nuclear Radiation

• By Abijith Singh
• Brian Carrion
• Sikender Shahid
• Qaim Ali
• Tony Lawrence

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What is Radioactivity?

• Radioactivity is a process in which unstable
  atomic nuclei become more stable by spontaneously
  emitting highly energetic particles and or energy.

http//10.200.10.53/videos/25514/sec18850_700k.asf

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Discovery

• Roentgen photographed his wifes hand using
  cathode rays. He discovered x-rays, a form of
  radiation.
• Becquerel discovered that uranium crystals left
  in sealed cabinets emitted their own energy,
  discovering natural radioactivity.
• Marie Curie and her husband Pierre measured the
  ability of emanations from various elements. They
  introduced radio-active when they realized that
  a pitchblende uranium formed 300 times current
  stronger than pure uranium.

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Radioactive Decay

• Radioactive decay occurs when the nucleus is not
  stable. This process does not require energy and
  the reaction is spontaneous. It involves the
  spontaneous transformation of one element into
  another.
• For example..

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Alpha Decay

• Alpha decay is a type of radioactive decay in
  which an atomic nucleus emits an alpha particle
  and transforms into an atom
• Alpha decay occurs because the nucleus has too
  many protons which cause excessive repulsion. In
  an attempt to reduce the repulsion, a Helium
  nucleus is emitted.

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Beta Decay

• A beta particle is an electron. It emerges from a
  weak decay process in which one of the neutrons
  inside an atom decays to produce a proton, the
  beta electron and an anti-electron-type neutrino.
  Some nuclei instead undergo beta plus decay, in
  which a proton decays to become a neutron plus a
  positron and an electron-type neutrino.

http//library.thinkquest.org/C0126323/beta_decay.
htm
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Gamma Decay

• Gamma decay is one of the three radioactive decay
  modes available to atomic nuclei.
• The nucleus in an excited energy state decays to
  a lower-energy state by emitting a high-energy
  photon.
• The decay process is very similar to the
  absorption and emission of light by atoms in the
  ultraviolet, visible, and infrared spectrums.

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Radioactive Elements

• Elements which either have no stable isotopes or
  have at least one naturally occurring isotope,
  are radioactive.
• http//www.theodoregray.com/PeriodicTable/Elements
  /Radioactives.html

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Smoke Detector

• The particles generated by americium are able to
  ionize the oxygen and nitrogen atoms of the air
  in the chamber.
• After ionizing an electron, you end up with a
  free electron and an atom missing one electron.
• The electronics in the smoke detector sense the
  amount of electrical current that these electrons
  and ions moving toward the plates represent.
• When smoke enters the ionization chamber, it
  disrupts this current. The smoke detector senses
  the drop and sets off the horn.

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Radiation Units

• The basic unit of radiation dose used to be the
  rad,'' defined in terms of the energy deposited
  by ionizing radiation per unit mass of exposed
  matter (e.g. flesh or bone)
• The RBEs of -rays, X-rays and -rays (fast
  electrons) are all 1 by definition thermal
  neutrons have an average RBE of 3 fast neutrons,
  protons and -rays (4He nuclei) all have RBEs of
  10 and fast heavy ions have an RBE of 20.9 A new
  unit was then constructed by combining the RBE
  with the dosage in rads, namely the rem (rntgen
  equivalent to man), defined by
• The R'' in the preceding paragraph stands for
  rem and the mR'' for millirem - one thousandth
  of a rem. Today the standard international unit
  for measuring effective dosage'' is the
  seivert. Converting between rem and seivert is
  just like converting between rad and gray

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Radiation Exposure

• Nuclear fallout of an atomic weapon
• Exposure in a nuclear power plant
• Cosmic and Ground Radiation
• House construction material
• Medical and dental X-rays

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Radiation Effects

• Less than a 100 REM temporary impairment of
  immune system
• 100-150 REM mild radiation sickness bone
  growth
• 150-650 REM radiation sickness
• 650-8000 REM delayed death in a week
• Above 8000 REM death immediately or in a day

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Geiger Counter

• Geiger counters are devices that detect
  radioactivity
• The Geiger Counter contains gas which is around a
  high-voltage electrode.
• When a particle or wave strikes one of the gas
  molecules, it triggers an avalanche effect that
  causes all the gas to ionize and to conduct
  electrical current.

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Use of Geiger Counters

• Everyday Uses
• Medicine
• Astronomy
• Geology

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Half-life

• Half-life length of time during which half of a
  given number of atoms of a radioactive nuclide
  decays.

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Half Life Equation
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Example

• If you originally had 157 grams of carbon-14 and
  the half-life of carbon-14 is 5730 years, how
  much would there be after 2000 years?

The answer is that there would be 123 grams left.
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Overall

• Nuclear radiation is basically radioactivity
  which is a process in which unstable atomic
  nuclei become more stable by spontaneously
  emitting highly energetic particles and or
  energy. Exposure to much radiation can result tin
  death.

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THE END