Desenvolvimento de um equipamento para dosimetria por luminescÃncia oticamente estimulada (LOE)

AUTOR(ES)

SÃrgio Torres de Santana

DATA DE PUBLICAÇÃO

2006

RESUMO

In recent years the Optically Stimulated Luminescence (OSL) has become a popular procedure for the dosimetry of the ionizing radiation. OSL arises from the recombination of charges which has been optically released from electron traps within the crystal. The electron population in the traps is the result of irradiation of the material, and thus the OSL intensity is related to the absorbed radiation dose. In this paper we describe the development of an equipment for the OSL dosimetry to be used in the Nuclear Energy Department of UFPE. The system is based on the pulse stimulation technique in which the stimulation source is pulsed and the OSL is measured only after the end of the pulse. The stimulation source used was an array of 20 Blue LEDs (with λ≈,470nm and Imax,50cd). To detect the OSL we used the photomultiplier tube Hamamatsu R980 which has a response curve with a maximum detection efficiency peaking around 420nm which is suitable for the luminescence emission spectra of Al2O3:C and quartz. The effects of stimulation light intensity and the pulse width on the OSL signal were investigated. The results showed that 500ms for the stimulation pulse width and 2s for the measurement of the OSL produced by the irradiated sample are adequate for the radiation dosimetry using pulsed optically stimulated luminescence. The application of the system developed for the Al2O3:C dosimetry was also investigated using Al2O3:C dosimeters irradiated with an x-ray beam and with a gamma beam of 137Cs. The results obtained showed that the dose response of Al2O3:C is linear over the region of the dose range that the experiment was carried out and the minimum detectable dose is 300μGy. The results obtained also showed that the pulsed OSL unit developed based on blue LEDs can be considered as a compact, reliable and inexpensive system for routine OSL measurements

ASSUNTO(S)

luminescÃncia oticamente estimulada engenharia nuclear pulsed pulsado radiation radiaÃÃo osl loe medidor de dose dose measurement optically stimulated luminescence

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