Robert L. Butenhoff worked in the Instrument and Physical Measurements Group in Clinton Laboratories at the X-10 Reactor. His group was led by Casimer J. Borkowski and he worked with Alan A. Jarrett and Jack D. East.
According to the Journal of Glenn T. Seaborg (Vol. 2), Butenhoff was transferred from the University of Chicago's Metallurgical Laboratory ("Met Lab") on September 6, 1943 (p. 115). He initially began working at the Met Lab in Section C-I on June 1, 1943. Butenhoff earned his B.S. in chemistry from North Central College in Naperville, IL (Seaborg, p. 40).
For more information about the Butenhoff and the personnel at the Met Lab, please see the following reference: