When heated, the electrons are released from these traps and return to their lowest energy state with the release of light. The amount of light released is proportional to the radiation exposure. This effect is caused by radiation induced changes in the glass crystalline electronic structure. Although other materials also exhibit this property, silver activated RPL glass has found the greatest application in x and gamma radiation dosimetry. The sensitivity depends on the type and manufacturer selected, and ranges from 0.01 cGy to several million cGy.
Silicon diodes are most useful for high energy neutron dosimetry.
Neutrons reacting in the diodes cause displacement of atoms in the silicon crystal which results in a relatively permanent and measurable change in its electronic resistance. These dosimeters are almost totally insensitive to x and gamma radiation and have a practical range of 1 to 1000 cGy depending on the type selected. The primary purpose of performing radiological surveys is to determine the extent of any existing health hazards, establish protective control boundaries, and provide data on which to base decontamination requirements. Various types of radiological surveys may be performed. Area surveys may involve the determination of fallout patterns on the ground, levels of airborne activity, or contamination patterns on ships or in buildings.