Building an Internal Conversion Electron Spectrometer with High Resolution for Analysis of Actinide Nuclides

大多数锕系核素是α发射体，并且由于它们的高内转换系数，锕系核素通常具有极低的光子强度。因此，α能谱法已被广泛用作标准分析工具，用于锕系核素的鉴定和分析，而不是γ能谱法。不幸的是，α射线光谱仪没有能力分离相差约10 keV的能量群。因此，很难分析诸如<@D1239@> D2 Pu和<@D1240@> D1 Pu的混合物。此外，物质中的高能量损失引起尾料以降低α射线谱中的能量，并且进一步对无限薄和失重的源提出关键要求。研制了一台采用无窗硅（锂）探测器的高能量分辨率内转换电子谱仪。能量分辨率为0.48 keV的FWHM为42 keV的电子。从光谱仪的检查，电子和伽马射线之间的能量分辨率的差异被发现主要是由于通过检测器的吸收层的电子的能量离散。从探测器内电子的后向散射和边缘电子的逃逸两个方面定量地解释了电子的相对效率曲线。用ICE光谱法对<@D1240@> D1 Pr与<@D1239@>D1同位素比值进行了分析，发现该比值的测定具有良好的准确度和精密度。

Most of the actinide nuclides are alpha-emitters and furter the actinide nuclides often have extremely low photon intensities due to their high internal conversion coefficients. Therefore, alpha ray spectrometry has been widely used as a standard analytical tool for identification and assay of actinide nuclides, instead of gamma ray spectrometry. Alpha ray spectrometer, unfortunately, has no capability to separate an energy group differing by about 10 keV. Then, it is difficult to analyze the mixtures such as <@D1239@>D2Pu and <@D1240@>D1Pu. Moreover, the high energy losses in a matter invoke tailings to lower energy in the alpha ray spectrum and further a critical requirement for an infinitely thin and weightless source. An internal conversion electron spectrometer with excellent energy resolution using a windowless Si(Li) detector was developed. The energy resolution was 0.48 keV in FWHM for 42 keV electrons. From the examination of the spectrometer, the difference of energy resolution between for electrons and for gamma rays was found to be predominantly due to the energy straggling of electrons through the absorbing layer of the detector. And the relative efficiency curve for electrons were quantitatively explained in terms of electron backscattering in the detector and electron escape from the edge. The analysis of the <@D1240@>D1Pr to <@D1239@>D1 isotope ratio was made by ICE spectrometry and it was found that the isotope ratio can be determined with excellent accuracy and precision.