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Cosmic Rays

18 Oct 2009, 21:01 UTC
Cosmic Rays
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Part 3 of my series on space radiation is about the radiation itself. The term cosmic rays is generally used to describe this radiation. Unfortunately, as often happens, the term evolved before the nature of the phenomenon being studied was known, so it may not be the best term to use. Nonetheless, we are stuck with it. In fact, the term has historically been used to describe more than one phenomenon.
About a century ago, when physicists were first seriously studying radiation and seeking to know the nature of this phenomenon, these researchers noticed that even when all known sources of radiation were removed from the vicinity of a radiation detection device that device still recorded a low level of radioactivity. Eventually, researchers began to realize that radioactive elements and isotopes were all around them. Even the materials used to shield against radiation, such as concrete blocks or lead plates, contained some radioactive isotopes. Some researches then began to wonder if air itself might contain a very small level of radioactivity. To isolate the radiation of just the air and not terrestrial surroundings, researchers put radiation detectors in balloons. As expected, the background radiation level dropped in the balloon flights ...

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