Padronização dos Radionuclídeos 201Tl e 55Fe em sistema de coincidências 4(PC)-NaI(Tl) / STANDARDIZATION OF 201Tl AND 55Fe RADIONUCLIDES IN A 4(PC)-NaI(Tl) COINCIDENCE SYSTEM

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

In the present work the procedure for the standardization of radionuclides using the 4(PC)-NaI(Tl) coincidence system was developed. The radionuclides selected were 201Tl, used in nuclear medicine, and 55Fe primary standard source, used for x-ray spectrometers calibration. The 4(PC)-NaI(Tl) is composed of a 4 proportional counter operated at 0.1MPa coupled to two NaI(Tl) crystals. The 201Tl decays by electron capture process followed by a prompt gamma-ray. The disintegration rate was determined by extrapolation technique using two methods: electronic discrimination and external absorbers. The radioactive sources were prepared in a 20 g cm-2 thick Collodion film. The conventional electronic system was used. The observed events were registered by the TAC method. The 55Fe decays by electron capture process to the ground state of 55Mn, emitting x-rays with around 6 keV. The standardization was obtained by the tracing method. This technique was applied using two radionuclides, which decay by electron capture process followed by a prompt gamma-ray, namely 51Cr and 54Mn, as tracers. Measurements with 1 and 2 aluminum foils, each 150 g cm-2 thick were carried out. The activity was obtained by extrapolation for zero thickness Al foil. The uncertainties were treated by means of matrix covariance methodology and takes into account all correlations involved.

ASSUNTO(S)

padronização tálio-201 ferro-55 ferro-55 padronização tálio-201 sistema de coincidências sistema de concidências

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