Collins S M, Pearce A K, Regan P H, Keightley J D
National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom.
National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom.
Appl Radiat Isot. 2015 Aug;102:15-28. doi: 10.1016/j.apradiso.2015.04.008. Epub 2015 Apr 15.
Precise measurements of the absolute γ-ray emission probabilities have been made of radiochemically pure solutions of (223)Ra in equilibrium with its decay progeny, which had been previously standardised by 4π(liquid scintillation)-γ digital coincidence counting techniques. Two high-purity germanium γ-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 γ-ray spectrometry measurements using the nuclear data evaluations of the Decay Data Evaluation Project exhibited a range of ~18% in the most intense γ-ray emissions (>1% probability) of the (223)Ra decay series. Absolute γ-ray emission probabilities and standard uncertainties have been determined for the decay of (223)Ra, (219)Rn, (215)Po, (211)Pb, (211)Bi and (207)Tl in equilibrium. The standard uncertainties of the measured γ-ray emission probabilities quoted in this work show a significant improvement over previously reported γ-ray emission probabilities. Correlation coefficients for pairs of the measured γ-ray emission probabilities from the decays of the radionuclides (223)Ra, (219)Rn and (211)Pb have been determined and are presented. The α-transition probabilities of the (223)Ra have been deduced from P(γ+ce) balance using the γ-ray emission probabilities determined in this work with some agreement observed with the published experimental values of the α-emission probabilities.
已对与衰变产物处于平衡状态的（223）Ra放射化学纯溶液的绝对γ射线发射概率进行了精确测量，这些溶液先前已通过4π（液体闪烁）-γ数字符合计数技术进行了标准化。使用了两台高纯度锗γ射线光谱仪，它们已使用一套一级和二级放射性标准进行了精确校准。将通过主要技术确定的活度浓度与使用衰变数据评估项目的核数据评估进行γ射线光谱测量的结果进行比较，发现在（223）Ra衰变系列最强的γ射线发射（概率>1%）中，两者相差约18%。已确定了处于平衡状态的（223）Ra、（219）Rn、（215）Po、（211）Pb、（211）Bi和（207）Tl衰变的绝对γ射线发射概率和标准不确定度。本工作中引用的测量γ射线发射概率的标准不确定度比先前报道的γ射线发射概率有显著改善。已确定并给出了放射性核素（223）Ra、（219）Rn和（211）Pb衰变的成对测量γ射线发射概率的相关系数。已根据本工作确定的γ射线发射概率，通过P（γ+ce）平衡推导出（223）Ra的α跃迁概率，并且观察到与已发表α发射概率的实验值有一定的一致性。
