a尖b尖的统计意义（核言碎语275）

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

Small neutron sources

小型中子源

• Neutron Generators. Neutrons are produced in the fusion of deuterium and tritium in the following exothermic reaction. 2D 3T → 4He n 17.6 MeV. The neutron is produced with a kinetic energy of 14.1 MeV. This can be achieved on a small scale in the laboratory with a modest 100 kV accelerator for deuterium atoms bombarding a tritium target. Continuous neutron sources of ~1011 neutrons/second can be achieved relatively simply.
• 中子发生器。氘和氚在随后的放热反应中聚变产生中子。²D ³T→⁴He n 17.6 MeV。产生的中子动能为14.1 MeV。这可以在实验室中用一个适度的100 kV氘原子轰击氚靶加速器小规模实现。可以相对简单地获得每秒约1011个中子的连续中子源。
• Radioisotope source – (α,n) reactions. In certain light isotopes, the ‘last’ neutron in the nucleus is weakly bound and is released when the compound nucleus formed following α-particle bombardment decays. The bombardment of beryllium by α-particles leads to the production of neutrons by the following exothermic reaction: 4He 9Be→12C n 5.7 MeV. This reaction yields a weak source of neutrons with an energy spectrum resembling that from a fission source and is used nowadays in portable neutron sources. Radium, plutonium, or americium can be used as an α-emitter.
• 放射性同位素源-（α，n）反应。在某些轻同位素中，原子核中的“最后”中子是弱束缚的，当α粒子轰击后形成的复合核衰变时释放出来。α粒子轰击铍通过以下放热反应产生中子：⁴He ⁹Be→¹²C n 5.7 MeV。该反应产生弱中子源，其能谱与裂变源的能谱相似，目前用于便携式中子源。镭、钚或镅可用作α发射体。

（待续）