What is TLD and what is a TLD badge?

Thermoluminescent (TL) means emitting light when heated. We can briefly describe the mechanism of TL as follow: When a strong energy source (such as ionizing radiation) hits a TL material, electrons are freed from some atoms and moved to other parts of the material, leaving behind “holes” of positive charge. Subsequently when the TL material is heated, the electrons and the “holes” re-combine, and release the extra energy in the form of light. The light intensity can be measured, and related to the amount of energy initially absorbed through exposure to the energy source. TLD badges are used to detect radiation at levels that can be harmful to humans. They emit light in amounts proportional to the radiation received. Thermoluminescent dosimeters (TLDs) are made from materials that measure cumulative exposure to ionizing radiation. They are worn for periods of approximately three months and are then processed to determine the dosage of radiation detected. TLD badges are logged to maintain cumulative records of an individual’s exposure to radiation over an extended period of time.