Berlizov A N, van Belle P, Zuleger E, Ottmar H
European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe, Germany.
Appl Radiat Isot. 2011 Feb;69(2):531-8. doi: 10.1016/j.apradiso.2010.11.017. Epub 2010 Nov 26.
Because of the very low specific activity of (242)Pu, the non-destructive assay of this isotope by means of conventional high-resolution gamma-spectrometry (HRGS) is possible only for Pu samples highly rich in (242)Pu. For bulk samples suffering from the gamma self-attenuation and self-fluorescence effects, the only practical choice for the quantitative analysis of (242)Pu is the weak γ-line emitted in the 159 keV transition of its α-decay daughter (238)U. A recent study revealed a significant disagreement between the (242)Pu mass values in a 99.72% enriched (242)PuO(2) sample as reported by HRGS and neutron coincidence counting. This fact motivated the present study on the experimental re-evaluation of the γ-emission probability for the 159 keV transition using a combination of α-, γ- and mass-spectrometry techniques. The obtained new emission probability P(2)=(2.20±0.08)10(-6) turned out to be ≈35% smaller than the currently adopted value. The study also suggested a new value E(2)=159.018±0.016 keV for the energy of the respective γ-ray.
由于（242）钚的比活度非常低，仅通过传统的高分辨率伽马能谱法（HRGS）对这种同位素进行非破坏性分析，仅适用于富含（242）钚的钚样品。对于受伽马自吸收和自荧光效应影响的大量样品，对（242）钚进行定量分析的唯一实际选择是其α衰变子体（238）铀在159 keV跃迁中发射的弱γ射线。最近的一项研究表明，HRGS报告的99.72%富集（242）PuO₂样品中的（242）钚质量值与中子符合计数之间存在显著差异。这一事实促使本研究采用α谱、γ谱和质谱技术相结合的方法，对159 keV跃迁的γ发射概率进行实验重新评估。获得的新发射概率P（2）=（2.20±0.08）×10⁻⁶，结果比目前采用的值小约35%。该研究还提出了相应γ射线能量的新值E（2）=159.018±0.016 keV。
