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Nuclear Radiation

Nuclear Radiation. By: Abijith Singh Brian Carrion Sikender Shahid Qaim Ali Tony Lawrence. What is Radioactivity?.

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Nuclear Radiation

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  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 wife’s 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. 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.

  19. THE END

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