这些物质被称作“放射性同位素”—同一种元素的变种，他们具有异常的中子数量，频繁的衰变和放出辐射。

These materials are known as "radioisotopes" -versions of an element that, because they have an abnormal number of neutrons, frequently decay and release radiation.

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该模型火车安装有合成的放射性同位素(中子或者说能量的来源)，在模型列车轨道上进行连续3天的循环，以协助通知其他聚变实验。

This model train was mounted with a synthetic radioisotope (a source of neutrons - or energy) and sent on a continuous three-day loop on hobby train tracks to help inform other fusion experiments.

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