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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Although such a cloud would pose virtually no threat while in the upper atmosphere, the fallout at the ground of radioactive particles from it should be a concern for any monitoring authority.

虽然这种云在高层大气中几乎不构成任何威胁，但是它在地面散发出的放射粒子的余波应该是任何监管机构所关注的。

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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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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