Precise measurements of the absolute gamma-ray emission probabilities of Ra-223 and decay progeny in equilibrium

摘要

Precise measurements of the absolute gamma-ray emission probabilities have been made of radiochemically pure solutions of Ra-223 in equilibrium with its decay progeny, which had been previously standardised by 4 pi(liquid scintillation)-gamma digital coincidence counting techniques. Two high-purity germanium gamma-ray spectrometers were used which had been accurately calibrated using a suite of primary and secondary radioactive standards. Comparison of the activity concentration determined by the primary technique against gamma-ray spectrometry measurements using the nuclear data evaluations of the Decay Data Evaluation Project exhibited a range of similar to 18% in the most intense gamma-ray emissions (>1% probability) of the Ra-223 decay series. Absolute gamma-ray emission probabilities and standard uncertainties have been determined for the decay of Ra-223, Rn-219, (215)po, Pb-211, Bi-211 and Tl-207 in equilibrium. The standard uncertainties of the measured gamma-ray emission probabilities quoted in this work show a significant improvement over previously reported gamma-ray emission probabilities. Correlation coefficients for pairs of the measured gamma-ray emission probabilities from the decays of the radionuclides Ra-223, Rn-219 an Pb-211 have been determined and are presented. The alpha-transition probabilities of the Ra-223 have been deduced from P(gamma+ce) balance using the gamma-ray emission probabilities determined in this work with some agreement observed with the published experimental values of the alpha-emission probabilities. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.