 A graduate of the University of Wisconsin – Madison , Creutz helped Princeton University build its first cyclotron . During World War II he worked on nuclear reactor design under Eugene Wigner at the Metallurgical Laboratory , designing the cooling system for the first water @-@ cooled reactors . He led a group that studied the metallurgy of uranium and other elements used in reactor designs . In October 1944 , he moved to the Los Alamos Laboratory , where he became a group leader . 
