otto hahn
He worked in London under Sir William Ramsay and worked under Ernest Rutherford at McGill University. With the help of Fritz Strassmann in 1938, he discovered fission of uranium and thorium. This phenomenon was explained later by Lise Meitner and Otto Robert Frisch. For this discovery, he was awarded the 1944 Nobel Prize for Chemistry, but wasn’t able to accept it because he was being held prisoner in Britain.