How was one [living in France] supposed to know whether or not to worry about a radioactive cloud?

怎能知道，[在法国生活]的人们应不应该为放射性尘埃担心呢？

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In Oslo, callers were on the phone to the State Institute for Radiation Hygiene afternews reports told of an invisible radioactive cloud over the most denselypopulated part of Norway.

在奥斯陆（译注：挪威首都），新闻中播报了放射云正在挪威人口最稠密地区上空的消息以后，挪威辐射卫生研究所的电话被打爆了。

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The positrons, produced by the decay of radioactive sodium, are cooled into a similarly sized cloud of around 1m particles and held in a neighbouring trap.

由放射性钠衰变产生正电子，冷却后形成一个由大约100万个正电子组成的体积同样大小的粒子云团，这团正电子被存放在相邻的一个容器中。

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That is why they drove straight into the radioactive cloud.

ECONOMIST: Banyan

In 1986, the fourth reactor at the Chernobyl nuclear complex in the Ukraine exploded and caught fire, spreading a radioactive cloud across Europe in the world's worst nuclear disaster.

CNN: Saturday,

The positrons, produced by the decay of radioactive sodium, are cooled into a similarly sized cloud of around 1m particles and held in a neighbouring trap.

ECONOMIST: Antihydrogen atoms are captured for the first time