Feasibility of using naturally occurring materials as dosimeters

A study of the thermoluminescent properties of locally available materials was made at the Philippine Atomic Energy Commission under a research contract from IAEA in order to develop radiation dosimeters. The materials studied were local ''kapiz'' (Placuna Placenta Linnasus), calcite, feldspar, eggshells and concrete. Processed samples of these materials were irradiated to various doses of Co-60 gamma rays and X-rays of different energies and their thermoluminescent characteristics were examined. Attempts were made to improve the sensitivity by adding MnC12 as an activator or by heat treatment. Fading characteristics were also studied by irradiating the samples to a single dose of radiation and then measuring the thermoluminescence at various time intervals. Of all the materials studied, kapiz has been found to be the most promising local material for developing radiation dosimeters. Its response is linear over a wide range of radiation doses, 50-104 R. Another advantage with kapiz is that it can be used in its original form. It shows very good reproducibility and has the lowest fading of all the materials tried. Another aspect of the research was the development of chemical dosimeters from locally available dyes. The chemical dosimeters were irradiated and then scanned with a spectrophotometer. The effects of light, temperature and pH on the stability of unirradiated dye were also investigated. Although the results of the studies show that chemical dosimeters from local dyes may be suitable, further investigations are necessary to improve their sensitivity