CHANGES IN ESR-SPECTRA OF POLY(METHYL METHACRYLATE) USED IN RETROSPECTIVE DOSIMETRY OF RADIATION ACCIDENTS

Poly(methyl methacrylate) was gamma-irradiated to a dose of 17 kGy. Th e ESR spectrum of free radicals was measured during a period of six we eks at temperatures in the range 20-40 degrees C. The observed ESR spe ctrum originates from contributions of a few types of free radicals. T he rate constants of decay of individual types of radicals are not equ al. Therefore, for this reason the form of the composite spectrum chan ges in the course of radical decay. It is pointed out that the relativ e changes in lines of the composite spectrum make it possible to deter mine the time of irradiation, and the change in intensity of the spect rum can be used for evaluating the absorbed dose. The changes in the f orm of ESR spectrum are discussed from the viewpoint of using them in retrospective ESR dosimetry subsequent to a radiation accident. (C) 19 98 Published by Elsevier Science Ltd. All rights reserved.