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Nuclear Radiation

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Nuclear Radiation By: Abijith Singh Brian Carrion Sikender Shahid Qaim Ali Tony Lawrence – PowerPoint PPT presentation

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Title: Nuclear Radiation


1
Nuclear Radiation
  • By Abijith Singh
  • Brian Carrion
  • Sikender Shahid
  • Qaim Ali
  • Tony Lawrence

2
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

3
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.

4
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..

5
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.

6
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
7
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.

8
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

9
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.

10
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

11
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

12
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

13
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.

14
Use of Geiger Counters
  • Everyday Uses
  • Medicine
  • Astronomy
  • Geology

15
Half-life
  • Half-life length of time during which half of a
    given number of atoms of a radioactive nuclide
    decays.

16
Half Life Equation
17
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.
18
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19
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.

20
THE END
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