Optically stimulated luminescence
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In physics, optically stimulated luminescence (OSL) is a method for measuring doses from ionizing radiation. It is used in at least two applications:
- Luminescence dating of ancient materials: mainly geological sediments and sometimes fired pottery, bricks etc., although in the latter case thermoluminescence dating is used more often
- Radiation dosimetry, which is the measurement of accumulated radiation dose in the tissues of health care, nuclear, research and other workers, as well as in building materials in regions of nuclear disaster
The method makes use of
The OSL dosimeter provides a new degree of sensitivity by giving an accurate reading as low as 1 mrem for x-ray and gamma ray photons with energies ranging from 5 keV to greater than 40 MeV. The OSL dosimeter's maximum equivalent dose measurement for x-ray and gamma ray photons is 1000 rem. For beta particles with energies from 150 keV to in excess of 10 MeV, dose measurement ranges from 10 mrem to 1000 rem. Neutron radiation with energies of 40 keV to greater than 35 MeV has a dose measurement range from 20 mrem to 25 rem. In diagnostic imaging, the increased sensitivity of the OSL dosimeter makes it ideal for monitoring employees working in low-radiation environments and for pregnant workers.[citation needed]
To carry out OSL dating, mineral grains have to be extracted from the sample. Most commonly these are so-called coarse grains of 100-200 μm or fine grains of 4-11 μm. Occasionally other grain sizes are used.[citation needed]
The difference between
Recent OSL dating of stone tools in Arabia pushed the "out-of-Africa" date hypothesis of human migration back 50,000 years and added a possible path of migration from the African continent to the Arabian peninsula instead of through Europe.[3][4]
The most widely-used OSL method is called single-aliquot regeneration (SAR).[5]
References
- .
- ^ "Mungo Man older than thought". cogweb.ucla.edu.
- ^ "Man Out Of Africa". Financial Times (requires registration). London. 2010-11-27.
- ^ Schmid, Randolph E. (2011-01-27). "Humans may have left Africa earlier than thought". Archived from the original on January 3, 2016.
- .