Measurement of the gamma-ray probability per decay of 186Re

In this paper the procedure followed by the Nuclear Metrology Laboratory (Laboratório de Metrologia Nuclear - LMN) at the IPEN, in São Paulo, for the standardization of the ¹⁸⁶Re and determination of the gamma emission probabilities per decay of the main gamma-ray energies of ¹⁸⁶Re, 137.15 keV from β⁻ decay and 122.6 keV from EC are presented. The activity measurement was carried out in a 4π (PC) β-γ coincidence system. The contribution from electron capture events in the proportional counter has been estimated by means of additional 4π(PC)β-γ HPGe coincidence measurements. The activity of the solution was determined by the extrapolation technique. The events were registered using a Time to Amplitude Converter (TAC) associated with a Multichannel Analyzer. The gamma emission probabilities per decay were determined by means of an HPGe spectrometer calibrated in the 81 keV to 1408 keV energy range, by measuring sealed ampoules of ⁶⁰Co, ¹³³Ba, ¹³⁷Cs and ¹⁵²Eu, standardized at the LMN.