ON THE FORMATION OF SHORTLIVED ABSORPTION CENTERS DURING IRRADIATION OF PLASTIC SCINTILLATORS

There is strong evidence that shortlived absorption centers are produc ed during the irradiation of plastic scintillators. A broad absorption band ranging from 450-750 nm with a peak at a wavelength of 575 nm ha s been observed during the irradiation of the scintillating fiber BCF- 12 with gamma rays. Considerable absorption was detected at extremely low doses (D approximate to 10 - 20 Gy). The transmission was measured during and after irradiation as a function of wavelength and time. Th e time dependence can be described quantitatively by a simple kinetic model.