RESUMO
Two absolute methods were used for standardizing the 65Zn solution received within the framework of the 2002-2003 full-scale BIPM comparison. The first method was the 4piPC-gamma-coincidence with efficiency extrapolation. The measurement conditions were adjusted so that the slope of the extrapolation curve was absent, which ensured that the measurement result did not depend on the positron branch intensity. When using the second method, the KX-gamma-coincidence counting with two NaI(Tl) scintillation crystals of different thicknesses, extrapolation was not needed, but a correction for the positron branch was necessary. It is shown that the 4piPC-gamma-coincidence method has a significantly larger uncertainty, and it is necessary to pay attention to the uncertainty component connected with setting the gamma-channel mode, which is characteristic for 65Zn only.
Assuntos
Algoritmos , Modelos Estatísticos , Contagem de Cintilação/métodos , Contagem de Cintilação/normas , Espectrometria gama/métodos , Espectrometria gama/normas , Radioisótopos de Zinco/análise , Radioisótopos de Zinco/normas , Calibragem/normas , Meia-Vida , Controle de Qualidade , Radiometria/métodos , Radiometria/normas , Padrões de Referência , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
A joint project has been established between VNIIM (D.I. Mendeleyev Institute for Metrology) and LNHB (Laboratoire National Henri Becquerel) to determine as accurately as possible the X- and gamma-ray emission probabilities of 154Eu. Point sources were prepared by VNIIM, and absolute measurements of activity per unit mass were undertaken by both laboratories using coincidence, anti-coincidence and 4pi-gamma counting methods. Other point sources and one aliquot were also prepared for precise gamma-ray spectrometry measurements. Absolute photon emission probabilities were determined with a maximum uncertainty of 0.5% for the most intense lines, supporting the development of this nuclide as a multigamma standard.
Assuntos
Algoritmos , Európio/análise , Európio/normas , Raios gama , Fótons , Espectrometria gama/métodos , Raios X , Meia-Vida , Padrões de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espectrometria gama/normasRESUMO
D.I. Mendeleyev Institute for Metrology (VNIIM) participated in two international comparisons of 204Tl and 89Sr solutions organized by the BIPM. The activity concentration was measured using the 4pi PC beta-counting method. Special attention was paid for investigating the dependence of the result on the inner diameter of the source support ring. For thin Al rings (100-200 microm), no dependence was detected. The beta-impurities in the 89Sr solution were determined using a scintillation plastic spectrometer. The combined standard uncertainty of the standardization of the 89Sr solution is 0.2%, and that for 204Tl is 0.4%.