Radiation-sensitive indicator based on radiation-chemical formation of acids in polyvinyl butyral films containing chloral hydrate

Radiation-sensitive indicators based on dyed polyvinyl butyral (PVB) containing acid-sensitive dye (bromophenol blue, BPB) and chloral hydrate (CCl3CH(OH)(2), 2;2,2-trichloroethane-1, I-diol) have been developed. These plastic film dosimeters undergo colour change from blue (the alkaline form of BPB) to yellow (the acidic form of BPB), indicating acid formation. The concentration of radiation-formed acids in the films containing different concentrations of chloral hydrate was calculated at different doses. The kinetics of the acid-formation reaction is discussed, indicating a half-order reaction with respect to chloral hydrate concentration. These films can be used as dosimeters for food irradiation applications where the maxima of the useful dose ranges are between 1 and 4 kGy depending oh chloral hydrate concentration in the film. The response of these films depends on temperature during irradiation; therefore a correction should be applied. These films have the advantage of negligible humidity effects on response in the intermediate range of relative humidity from 10 to 70% as well as good post-irradiation stability when stored in the dark at room temperature. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.