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Thermoluminescent personnel dosimetry system design for mixed radiation fields

Thesis/Dissertation ·
OSTI ID:6833338

A thermoluminescent badge system for personnel dosimetry is designed based on the dosimetric properties of CaSO{sub 4}:Dy TLD material. This material is characterized by an enhanced over-response to gamma radiation with energies below 200 KeV. Different filter combinations are used in four separate areas of the badge system to compensate for this energy over-response and to provide a measurement of radiation dose received during field exposure. The four badge areas house the open window, beta shield, bias filter and the deep dose areas. The response of the TLD material under these areas is used to measure two primary dosimetric quantities, the deep dose and the shallow dose equivalents delivered to tissue at the depths 1.0 cm and 0.007 cm respectively. The deep dose area of the badge (i.e. A4) is designed to give a direct measurement of the deep dose delivered during radiation exposure to photons with energies in the range 15 to 662 KeV. The badge is also designed to resolve mixed beta/gamma radiation fields by utilizing the response of the open window and the beta shield areas. The capability of the badge system to resolve mixed gamma radiation fields is examined in a theoretical situation where a low energy x-ray component is mixed with a Cs{sup 137} gamma component. The greatest sensitivity of the badge in such situations is when the low energy component has an effective photon energy lower than 40 KeV. This limit is set by the observed flat photon energy response of the difference ratios at energies higher than 40 KeV.

Research Organization:
Washington Univ., Seattle, WA (USA)
OSTI ID:
6833338
Country of Publication:
United States
Language:
English