الفهرس 
AIM OF THE WORKOnly 14 pages are availabe for public view
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Abstract
A new EPR dosimetry system has been developed based on the radiation-formed stable paramagnetic centers in quartz. The first part of the thesis includes the preparation of quartz rods (diameter = 3 mm, length = 10 mm) where quartz powder was mixed with molten mixture of paraffin wax and Ethylene Vinyl Acetate Copolymer (EVA). The binding-mixture EVA / paraffin do not present interference or noise in the Electron Paramagnetic Resonance (EPR) signal before or after irradiation to high doses. Quartz used in this study is obtained from two different sources where denoted as (q1, q2). The quartz samples (q1, q2) rods were prepared by concentration 20%. The rods show good mechanical properties for safe and multi-use handling. The second part is concerned with studying the dosimetric characteristics of gamma irradiation sensitive rods where the radiation-formed stable free radicals (E′-center, peroxy radical and non-bridging oxygen hole center) which analyzed by using EPR spectrometer. Unirradiated rods have no EPR signals. The useful dose range of these rods was found to range from 0.1 to 15 kGy for q1 and from 0.1 to 25 kGy for q2 depending on concentration of quartz powder, indicating their suitability for low and high dose gamma radiation applications. The dosimeter response was assessed using the peak-to-peak amplitude of the first-derivatives EPR spectrum. Its EPR signal was found unchanged in shape with different doses and different concentrations. A signal line spectrum attributed to the E′-center was observed after irradiation, and this radical is insensitive to temperature, light independence. The overall uncertainty for quartz rod dosimeters (q1, q2) at 2σ (σ is standard deviation) was found to be 4.55 % for q1 and 5.94 % for q2. The dosimetric parameters, e. g. dose response, effect of temperature during irradiation on response, influence of humidity, energy dependence as well as pre- and post-irradiation stability at different storage conditions are discussed.