差异处于显著性边缘的意义（核言碎语276）

193 按源的显著性分类

Classification by significance of the source

（https://www.nuclear-power.com/）

按源的显著性分类

• Radioisotope source – (γ,n) reactions. (γ,n) reactions can also be used for the same purpose. In this type of source, because of the greater range of the γ-ray, the two physical components of the source can be separated, making it possible to ‘switch off’ the reaction if so required by removing the radioactive source from the beryllium. (γ,n) sources produce monoenergetic neutrons, unlike (α,n) sources. The (γ,n) source uses antimony-124 as the gamma emitter in the following endothermic reaction.
• 放射性同位素源-（γ，n）反应。（γ，n）反应也可用于相同目的。在此类源中，由于γ射线的射程更大，源的两个物理部分可以分离，如果需要时可以通过从铍中移除放射源来“关闭”反应。（γ，n）源产生单能中子，与（α，n）源不同。（γ，n）源在以下吸热反应中使用锑-124作为γ发射体。

¹²⁴Sb→¹²⁴Te β− γ

γ ⁹Be→⁸Be n–1.66 MeV

• Radioisotope source – spontaneous fission. Certain isotopes undergo spontaneous fission with the emission of neutrons. The most commonly used spontaneous fission source is the radioactive isotope californium-252. Cf-252 and other spontaneous fission neutron sources are produced by irradiating uranium or another transuranic element in a nuclear reactor, where neutrons are absorbed in the starting material and its subsequent reaction products, transmuting the starting material into the SF isotope.
• 放射性同位素源——自发裂变。某些同位素可通过自发裂变而发射中子。最常用的自发裂变源是放射性同位素锎-252。Cf-252和其他自发裂变中子源是通过辐照核反应堆中的铀或其他超铀元素产生的，此处中子被起始材料及其后续反应产物吸收，将起始材料转化为SF同位素。

（待续）