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Around the beginning of the twentieth century , it was found that under certain conditions a fast-moving charged particle caused a condensation of supersaturated water vapor along its path. In 1911 , Charles Wilson used this principle to devise his cloud chamber so he could photograph the tracks of charged particles , such as fast-moving electrons .
 Charles Wilson
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
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Text: {0} 
Answer:
 Charles Wilson