Exposure control, radiation gamma

Gamma irradiation The isotope Co is used as radiation source. A typical dose rate is 2 kGy/h. The dose is controlled by the exposure time and measured with a dosimeter. 

The quality control checks whether the product has been irradiated homogeneously and received the correct dose. The controllable variables are the source intensity and the exposure time. The process control is performed with a dosimeter, for example plates of polymethylmethacrylate (PMMA) that discolours under the influence of gamma radiation. The extent of discolouration is dependent on the absorbed dose. In one container several dosimeters are placed, which are analysed in the quality control laboratory afterwards in a spectrophotometer. 

The two principal specific license radiation sources used in semiconductor manufacturing are kr3 ton-85 gas (up to 50 curies) used in fine leak testing systems and cobalt-60 (up to 26,000 curies) used in irradiators for testing the ability of ICs to withstand exposure to gamma radiation in military and space applications. Under normal conditions, personnel exposures from these operations are t5 ically less than 500 millirems per year.0 1 Controls forthese systems include ... 

Rodenticide A pesticide used to control rodents. Roentgen (R) The unit of radiation exposure in the air units for quantities of X-ray or gamma radiation measured by detection and survey meters. Named after Wilhelm Roentgen, Gennan scientist who discovered X-rays in 1895. 

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