Thermoluminescent dosimeter

A thermoluminescent (TLD) is a dosimeter which can be used for measurement of ionizing radiation.

In addition to the age determination in archeology, the thermoluminescence is mainly used in radiation therapy, where it is becoming more and more important also in radiation protection measurements.

In this case, properties such as high radiation sensitivity, relatively large measurement range and the high energy independence, low fading, and thus the storage capacity for a long time, as well as the small geometric dimensions used.

After a thermoluminescent material has been exposed to the enabled over a certain period of ionizing radiation, it sends at thermal energy input from electromagnetic waves in the visible light region.

The amount of light emitted is directly proportional to the absorbed energy.

Because it is a relative measurement method in the thermoluminescence, to achieve an absolute value, a relatively complicated calibration is necessary.

There are in principle many materials for thermoluminescence, such as lithium fluoride, manganese active calcium sulfate or calcium fluoride, natural fluorite, lithium borate or beryllium.

1950 lithium fluoride has been proposed in the United States of Daniels for solid state dosimetry. We have developed the most diverse areas of application for these Dosimetergeneration, such as the dating of ceramics in art history, the exploration of the moon or the detection of possible volcanic activity.

The main item under the TLD materials takes the one with magnesium and titanium doped lithium fluoride. This follows from the long experience of the dose determination with this detector system and the high level of development, enables the measurements with high precision.

A further improvement of the material could be achieved by other dopants. So you could see another increase in sensitivity when doped with magnesium, copper and phosphorus, lithium fluoride. This material was first developed in 1978 in the PRC in powder form. 1986, it was investigated in solid form, and presented in 1992 in Washington at the 10th Congress of the solid state dosimetry.

By comparing the different signal LiF TLDs in which one enriched with lithium 6 (TLD -600 ) and the other having a reduced concentration of lithium-6 - (TLD -700), one can estimate the dose of thermal neutrons, as only Li -6 captures neutrons and then decays by alpha particle emission in boron. The alpha particles ionize then along the particle track detector.