Radiation sensitive indicator based on dyed polyvinyl alcohol (PVA) containing acid – sensitive dye (bromo-chloro-phenol blue, BCPB) and chloral hydrate has been developed. These plastic film dosimeters undergo color change from blue (the alkaline form of bromo-chloro-phenol blue, BCPB) to yellow (the acidic form of bromo-chloro-phenol blue, BCPB), indicating acid formation. The concentration of formed acids in the films containing different concentrations of chloral hydrate was calculated at different doses. These films can be used as dosimeters for food dosimetry applications where the maximum of the useful dose ranges are between 1-10 kGy depending on chloral hydrate concentration in the film. The films have the advantage of negligible humidity effects on response in the range of relative humidity from 0 to 100% as good post irradiation stability when stored in the dark at room temperature. The energy band gap of the prepared films was calculated and the effect of gamma radiation on its value was determined. Direct and indirect transitions were illustrated from the absorption spectra.

Sayeda Eid, Wafaa Beshir and Seif Ebraheem