Radiation and its uses

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  • Created by: R.Perkins
  • Created on: 04-03-14 17:44

Alpha Radiation

  • Highly energetic helium particle - it's of a positive charge and boasts 2 neutrons and 2 protons.
  • Can only travel for a few centimetres in air and can be absorbed by a thin sheet of paper and skin - because of its strong positive charge, the radiation ionises other atoms quickly (knocks off electrons). The radiation loses energy quickly, because of this.
  • Alpha particles cannot penetrate the skin (least penetrating form of radiation) - if they do enter the body however, the radiation can ionise large numbers of cells within a short distance. (Ionised cells can mutate - cause cancer)
  • PRECAUTIONS - This form of radiation can be handled with gloves but must no be inhaled, consumed or placed near eyes/open cuts
  • USES - Useful for smoke detectors - Americium releases alpha radiation, which ionises the air within the detector. As smoke from a fire absorbs this form of radiation, the alarm is triggered.
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Beta Radiation

  • Electron  released from the nucleus of an atom.
  • When this type of radiation is produced, one of the neutrons, within the nucleaus, divides into a proton and an electron. The high speed electron, formed here is the the beta particle.
  • Particles of a small negative charge - they ionise rather easily and can travel through thin materials. (Eg. Thin metal and paper)
  • The particles are much more penetrating than those of alpha radiation - can travel through skin; difficult to prevent this entering the body; less ionising than alpha particles.
  • PRECAUTIONS - Those handling beta radiation need to hold the source using tongs, away from the body
  • USES - Tracers (doctors use this for medical images; chemicals focus on damaged areas of the body - use of detectors allows images to be created, providing a clear insight into the workings of the body)  and monitoring material thickness.
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Gamma Radiation

  • High frequency (large amounts of energy in a short amount of time)
  • Short wavelength
  • Difficult to absorb but can penerate most materials (passes through skin, dense metals and concrete)
  • PRECAUTIONS - Sources of gamma radiation need to be held with tongs, away from the body and other people; those carrying the substance boast lead lined clothes, to reduce the amount of waves passing through the body.
  • USES - Sterilysing food and surgical equipment; treatment of cancer; testing of medical equipment
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Half Lives

  • "Time taken for the radioactivity to decrease to half of its orignal value,"
  • Should a radioactive isotope emit an alpha (2 ps, 2 neuts) or beta (single highly charged electron) particles, the result is a different isotope (as its atomic structure has varied).
  • As the decay continues, the number of nuclei, within the isotope of the element, decreases.
  • Radioactivity or 'number of counts' is measured in Becquerels (Bq) (Measure the time taken after every 'half' -  how long does it take before 80 becomes 40, 20 becomes 10)

The rate of decay depends on numerous factors:

  • Type of material/element
  • The number of nuceli within the radioactive isotope (greater the amount, greater the rate of decay)

Alpha Decay Formula: (Radon becomes polonium + helium)        Beta Decay Formula - Carbon 14 (as a proton and electron are formed from the neutron, the proton number increases)

219 / 86 Rn -> 215 / 84 Po + 4 / 2 He (http://www.bbc.co.uk/schools/gcsebitesize/science/images/addgateway_rnpohe.gif)                                           14 / 6 C leads to 14 / 7 N + 0 / -1 e - (http://www.bbc.co.uk/schools/gcsebitesize/science/images/addgateway_cne.gif)

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