The Concentration Determination for High Atomic Number Elements by <gamma>-Ray Excited DX-Ray Spectrometry

为了测定高Z元素的浓度，用高纯锗半导体探测器，研究了用Cs-137伽马射线源(半衰期为30.17年，662keV；伽马射线)非色散光谱的KX荧光技术。用这种技术分析装在容器或管道中的样品是可能的。Cs-137；伽马射线有足够的能量激发高Z元素的KX光，但在样品中产生相当数量的康普顿散射伽马射线，并且要求KX光与样品的散射辐射的大比例具有足够的准确度。在这种方法中，通过设置光源、样品和X射线探测器之间的几何结构来减少散射辐射以提高比值，样品条件如密度、颗粒尺寸、基质组成的变化对与浓度-KX-射线/康普顿计数比有关的特性校准曲线有很大影响。300秒的测量允许对粉末、水溶液和所有含有超过几个wt%W、Pb或U的合金样品的相对精度低于3%。

In order to determine the concentration of high Z elements, KX-ray fluorescence technique by using a Cs-137 <gamma>-ray source (half-life 30.17 years, 662 KeV <gamma>-ray) with non-dispersive spectrometry using a high pure germanium semiconguctor detector is investigated. It is possible with this technique to analyse the specimens enclosed in containers or pipe lines.The Cs-137 <gamma>-ray has enough energy to excite the KX-rays of high Z elements, however considerable amount of Compton scattered <gamma>-rays in specimens is produced, and large ratio of the KX-rays to the scattered radiation from specimens is required to have sufficient accuracy. In this method, the scattered radiation should be reduced to improve the ratio by setting up the geometry between the source, specimen and X-ray detector.The variation of specimen conditions such as density, particle size, matrix composition affect much on the characteristic calibration curves related to the concentration vs. KX-ray/Compton count ratio. The 300 second measurement allows the relative precision of less than 3% for powder, aqueous solution, and all alloy specimens containing more than a few wt% W, Pb or U.