Science Form 5 Questions from Li Wei

Posted on June 1 2010 by


Carbon-14, 14C, or radiocarbon, is a radioactive isotope of carbon with a nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method to date archaeological, geological, and hydrogeological samples. Carbon-14 was discovered on 27 February 1940, by Martin Kamen and Sam Ruben at the University of California Radiation Laboratory in Berkeley, although its existence had been suggested by Franz Kurie in 1934. – Usually used by archeologist to identity the age of prehistoric items or remains

Cobalt-60 (60Co) is a radioactive isotope of cobalt. Due to its short half life of 5.27 years 60Co is not found in nature. It is produced artificially by neutron activation of 59Co. 60Co decays by negative beta decay to the stable isotope nickel-60 (60Ni). The activated Ni-atom emits two gamma rays with energies of 1.17 and 1.33 MeV.

Main uses for 60Co:

  • As a tracer for cobalt in chemical reactions,
  • Sterilization of medical equipment,
  • Radiation source for medical radiotherapy,
  • Radiation source for industrial radiography,
  • Radioactive source for leveling devices and thickness gauges,
  • As a radioactive source for food irradiation and blood irradiation, and
  • As a radioactive source for laboratory use.

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