WILLIAM DE SOUZA SANTOS
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Artigo IPEN-doc 25797 Monte Carlo modeling of a holder for irradiation of dosimeters in beta radiation beams2019 - POLO, IVON O.; SANTOS, WILLIAM S.; CALDAS, LINDA V.E.A study of the influence of a dosimetric holder and its cover for the irradiation of the dosimeters in the Beta Secondary Standard BSS2 radiation fields is reported. The correction factors for attenuation or scattering were calculated taking into account the BSS2 beta source energy, as well as the detector source distance. The study and the determination of these factors were carried out using the Monte Carlo Method. The results of the correction factors showed that the absorption and scattering of the electrons depend greatly on the energy of beta radionuclides. The determined correction factors are in agreement with the international report ISO 6980.Artigo IPEN-doc 25131 Modelling the absorbed dose rate of the beta standard BSS2 147Pm source2018 - POLO, IVON O.; SANTOS, WILLIAM S.; CALDAS, LINDA V.E.The dosimetric measurements of 147Pm beta radiation beams have limitations due to their low energy, low dose rate, great dispersion and attenuation in air or tissue. In this work, the Monte Carlo model was developed for a 147Pm absorbed dose rate determination. This model consists of an extrapolation chamber and a 147Pm beta radiation source. Moreover, the absorbed dose rate was determined by experimental measurements and the MCNP Monte Carlo code was used. The relative number of particles that crossed the radioactive source window and the particles that crossed the extrapolation chamber entrance window were determined. The source fluence spectrum was also determined. The results of the simulation and the experimental calculations are in agreement with the absorbed dose rate from the PTB calibration certificate. The results obtained are considered acceptable, and they agree within the uncertainties. The difference between the experimental result and that from the Monte Carlo model, compared to that from the calibration certificate, was only 0.8% in both cases.Artigo IPEN-doc 25130 Determination of correction factors in beta radiation beams using Monte Carlo method2018 - POLO, IVON O.; SANTOS, WILLIAM de S.; CALDAS, LINDA V.E.The absorbed dose rate is the main characterization quantity for beta radiation. The extrapolation chamber is considered the primary standard instrument. To determine absorbed dose rates in beta radiation beams, it is necessary to establish several correction factors. In this work, the correction factors for the backscatter due to the collecting electrode and to the guard ring, and the correction factor for Bremsstrahlung in beta secondary standard radiation beams are presented. For this purpose, the Monte Carlo method was applied. The results obtained are considered acceptable, and they agree within the uncertainties. The differences between the backscatter factors determined by the Monte Carlo method and those of the ISO standard were 0.6%, 0.9% and 2.04% for 90Sr/90Y, 85Kr and 147Pm sources respectively. The differences between the Bremsstrahlung factors determined by the Monte Carlo method and those of the ISO were 0.25%, 0.6% and 1% for 90Sr/90Y, 85Kr and 147Pm sources respectively.