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French scientists Hans von Halban , Lew Kowarski , and Frédéric Joliot-Curie had demonstrated that uranium bombarded by neutrons emitted more neutrons than it absorbed , suggesting the possibility of a chain reaction .
 Hans von Halban, Lew Kowarski, Frédéric Joliot-Curie
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Hans von Halban, Lew Kowarski, Frédéric Joliot-Curie