Thermoluminescence dating

Description

A dating method that measures the amount of light released when an object is heated. Thermoluminescence, or TL, has been used since the 1950s to determine the approximated firing date of pottery and burnt silicate materials. TL has a wide dating range; it has been used to date ceramics from a few hundred years old to geologic formations that are half a million years old. The technique measures the small amount of energy that continually builds up in the mineral crystal lattice. When heated, this energy is released as a burst of light. The intensity of the light is proportional to the amount of energy, which in turn corresponds to the length of accumulation time. Thus the time can be approximated for original original firing date. Recently new techniques (optically stimulated luminescence dating) using lasers and sensitive detectors have been used to improve the light detection. Samples require about 100 milligram and the sample collection and handling step is critical. The accuracy of the technique is about 10%. The rate of energy accumulation depends on the amount of background radiation to which the object has been exposed. Thus, radiography can slightly increase the amount of accumulated energy.

Synonyms and Related Terms

TL; optically stimulated luminescence dating; Thermolumineszenzdatierung (Deut.); datation par thermoluminescence (Fr.); termoluminescenza (It.)

Additional Information

° Roy Switzur "Dating Techniques" Building Conservation Directory 2001: Link (lists analysis labs in England)

Authority

• Caring for your Collections, Arthur W Schulz (ed.), Harry N. Abrams, Inc. , New York, 1992

• Website address 1 Comment: Building Conservation Directory - http://www.buildingconservation.com/articles/dating%20technology/dating%20technology.htm

• External source or communication Comment: Tom Chase, CoOL DISTLIST, 5/1/01 - "X-radiography can affect the TL date. In the case of bronze objects with clay cores, I remember Sstuart Fleming saying that one normal radiograph adds about 5 years....."

• The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998

• Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000