Feasibility of a Hand-Held Integrating Dosimeter Using a Cadmium Telluride Detector

The objective of this contract was to conduct research leading to the development of a real-time, hand-held, integrating dosimeter for the measurement of ionizing radiation doses to the crews of high-altitude aircraft and space flights. The specific method chosen was the use of a cadmium telluride detector with appropriate circuitry and computer processing to determine the total energy deposited in the detector. The raw spectra from energy deposited in the detector, and the rate of energy disposition. These unmodified results were found to have a strong dose rate dependence above about 1 radhr. This dependence was removed through the use of an empirically determined correction based on the dead time of the MCA during spectrum acquisition. With this correction applied to all data the system response was highly linear with respect to dose rate and total dose and showed no energy dependence over the range of gamma ray energies from 186 keV to 1250 deV. The results support the feasibility of the method and suggest that further development would lead to a real-time electronic dosimeter capable of approximately tissue-equivalent response to a wide range of radiation types in mixed fields.