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From our results, we infer that 0.5 mM is the optimal concentration in polymer gel to obtain good DEEs in the energy range of 1.25 MeV.

Dose-rate dependence of PAGAT polymer gel dosimeter evaluated using X-ray CT scanner P Sellakumar, E James Jebaseelan Samuel and D Senthil Kumar inAbstract. Extract from Green Tea (GTE) acts as an antioxidant in acrylamide based polymer gel dosimeter. In this work, PAGAT gel was used for investigation of antioxidant effect of GTE.PAGAT was called PAGTEG (Polyacrylamide green tea extract gel dosimeter) after adding GTE. Free radicals in water cause pre polymerization of polymer gel before irradiation. Polyphenols from GTE are highly effective to absorb the free radicals in water. THPC is used as an antioxidant in polymer gel dosimeter but here we were replaced it by GTE and investigated its effect by spectrophotometer. GTE added PAGAT samples response was lower compared to THPC added sample. To increase the sensitivity of the PAGTEG, sugar was added. This study confirmed that THPC was a good antioxidant for polymer gel dosimeter. However, GTE also can be used as an antioxidant in polymer gel if use less quantity (GTE) and add sugar as sensitivity enhancer.

Abstract. The aim of this study is to evaluate the water equivalency of metal doped PAGAT gel dosimeter in terms of its effective atomic number. Auto-Zeff software and NIST XCOM data base were used to perform this study. Initially Gold (Au) and Silver (Ag) were taken and divided into different concentration (from 0.01 to 100Mm) with standard PAGAT formalism and the elemental composition was determined. Using these elemental compositions Zeff was generated for photon interaction using Auto-Zeff software. Au doped gel was found as a water equivalent in the concentration range of 0.01 to 0.1Mm. Ag doped gel have matched well with water from 0.01 to 1Mm concentration in terms of water equivalence. In these concentrations, it has been concluded that metal doped gel is more water equivalent than plain PAGAT gel based on the Zeff data obtained. IntroductionEffective atomic number (Zeff) is an important parameter to consider a material to be substituted for water for radiation dosimetry [1,2]. Many researchers reported the method of finding Zeff for a compound or mixture [3,4]. Zeff of any medium depends on the energy of the incident photon beam so, a single number cannot be a representative of Zeff of a compound material [4]. Hence Zeff depends on the photon energy, it is mandatory to compute the Zeff with respect to different range of energy. There are well reported publications available regarding Zeff of different gel dosimeter [5][6][7]. As per the best knowledge of the author there is no publication of computing Zeff for metal doped PAGAT gel dosimeter [8][9][10][11]. Recently metal nano particles (MNP) are an interesting candidate for dose enhancement effect (DEE) study in gel dosimeter [12,13]. MNPs increase the probabilities of photon interaction cross sections due to their high atomic number (high Z) and yield greater secondary radiations within the gel causing DEE. Different types of MNPs were reported for gel dosimeter such as Gold (Au, Z=79), Silver (Ag, Z=47), Platinum (Pt, Z=78) and Bismuth (Bi, Z=83) [14][15][16][17] for DEE. Though DEE is a great advantage by MNPs, its high Z presence in the gel should be evaluated to consider the MNP doped gel for water equivalency. In this study, Zeff parameter was studied for evaluating the water equivalency of metal doped PAGAT gel dosimeter.

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