engleski

TL and RPL detectors in mixed field dosimetry

Dosimetry of mixed neutron + gamma radiation field, due to the inherent complexity, is still a demanding task. In this paper the results of an investigation of LiF:Mg, Ti thermoluminescent (TL) detectors and radiophotoluminescent (RPL) glasses for use in mixed field dosimetry are shown. Lithium fluoride is the most widely used TL dosimeter. Especially, LiF TL detectors doped with Mg and Ti, owing to their glow curve characteristics, give possibilities for the separate determination of gamma and neutron dose components with a single detector. The short overview of the use of LiF:Mg, Ti based TL detectors in mixed field dosimetry is presented. Subsequently, the experimental data of the use of TL followed by phototransferred thermoluminescence (PTTL) in different mixed neutron + gamma ray fields, are presented and discussed. The results show that it is in principle possible to determine separately gamma and neutron dose components with a single detector due to different sensitivities of TL and subsequent PTTL to neutrons in comparison to gamma rays. Radiophotoluminescent (RPL) glass dosimeter type SC-1 has been studied with respect to its use as a photon dosimeter in mixed neutron + gamma fields. SC-1 is composed of the flat glass element placed in a plastic capsule. Energy compensation tin filters shield the glass card in the capsule from all directions. This type of dosimeter was primarily designed for the measurements of photon dose and for use in environmental monitoring around nuclear plants and for accident dosimetry. For a gamma dosimeter to be useful in a mixed neutron + gamma field it is desirable that the neutron sensitivity is small and accurately known. The response has been characterized for 14.5 MeV neutrons, 238Pu-Be spectra and thermal neutrons. The comparison with TLD-700 shows lower responses to neutrons for all investigated spectra giving advantage to the use of RPL dosimeter type SC-1 for photon dosimetry in mixed neutron + gamma fields.

TL; RPL; mixed field dosimetry

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