2011 International Nuclear Atlantic Conference - INAC 2011 Belo Horizonte,MG, Brazil, October 24-28, 2011 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: 978-85-99141-04-5 HIGH DOSE DOSIMETRY USING ANTIGORITE-TEFLON COMPOSITE René R. Rocca 1, Sonia H. Tatumi 2 and Shigueo Watanabe 1 1 Instituto de Física Universidade de São Paulo Rua do Matão 187 – Travessa R. 05508-090 Butantã, SP
[email protected] –
[email protected] 2 Faculdade de Tecnologia de São Paulo CEETESP Pça. Cel. Fernando Prestes - Bom retiro, 30 01124-060 São Paulo, SP
[email protected] ABSTRACT Pellets of antigorite crystals (Mg 3-x [Si 2O5] (OH) 4-2x ) and teflon powder were obtained in order to investigate the thermoluminescence (TL) dosimetric characteristics. ICP analysis was performed showing the presence of 0.25 mol% of Fe 2O3, 0.07 mol% of Al 2O3 and 0.006 mol% of MnO impurities. These pellets show two prominent TL peaks at 150 oC and another broad one at 250 oC observed in samples previously irradiated with gamma-rays from 60 Co source. The 150 oC peak increased up to 2 kGy and after this dose the intensity reaches a maximum then decreases gradually. However the 250 oC peak increased up even with a dose of 172 kGy. A good reproducibility of TL results was obtained showing that these pellets can be used for high dose measurements. An excellent theoretical fit using second order kinects model [10] was obtained for all the peaks; however the theoretical deconvolution [4] showed the presence of two additional peaks at 206 and 316 oC.