Losko A S, Vogel S C
Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
Forschungs-Neutronenquelle Heinz Maier-Leibnitz, 85748, Garching, Germany.
Sci Rep. 2022 Apr 22;12(1):6648. doi: 10.1038/s41598-022-10085-3.
Tools for three-dimensional elemental characterization are available on length scales ranging from individual atoms, using electrons as a probe, to micrometers with X-rays. However, for larger volumes up to millimeters or centimeters, quantitative measurements of elemental or isotope densities were hitherto only possible on the surface. Here, a novel quantitative elemental characterization method based on energy-resolved neutron imaging, utilizing the known neutron absorption cross sections with their 'finger-print' absorption resonance signatures, is demonstrated. Enabled by a pixilated time-of-flight neutron transmission detector installed at an intense short-pulsed spallation neutron source, for this demonstration 3.25 million state-of-the-art nuclear physics neutron transmission analyses were conducted to derive isotopic densities for five isotopes in 3D in a volume of 0.25 cm. The tomographic reconstruction of the isotope densities provides elemental maps similar to X-ray microprobe maps for any cross section in the probed volume. The bulk isotopic density of a U-20Pu-10Zr-3Np-2Am nuclear transmutation fuel sample was measured, agrees well with mass-spectrometry and is evidence of the accuracy of the method.
用于三维元素表征的工具可在从单个原子（使用电子作为探针）到微米级（使用X射线）的长度尺度上使用。然而，对于高达毫米或厘米级的更大体积，迄今为止，元素或同位素密度的定量测量仅能在表面进行。在此，展示了一种基于能量分辨中子成像的新型定量元素表征方法，该方法利用已知的中子吸收截面及其“指纹”吸收共振特征。通过安装在强短脉冲散裂中子源处的像素化飞行时间中子透射探测器，为此次演示进行了325万次先进的核物理中子透射分析，以在0.25立方厘米的体积内三维推导五种同位素的同位素密度。同位素密度的断层重建为探测体积内的任何横截面提供了类似于X射线微探针图的元素图。测量了U-20Pu-10Zr-3Np-2Am核嬗变燃料样品的整体同位素密度，与质谱法结果吻合良好，证明了该方法的准确性。
