Kenneth Greisen

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Kenneth Ingvard Greisen (24 January 1918 in Perth Amboy, New Jersey – 17 March 2007 in Ithaca, New York)^[1] was an American physicist who worked on nuclear physics and the astrophysics of cosmic rays and gamma radiation. "He will be most remembered for his realization that the cosmic microwave background limits the high-energy end of the spectrum of cosmic ray protons."^[2]