Alan A. Jarrett was a research assistant the University of Chicago's Metallurgical Laboratory ("Met Lab") during the Manhattan Project. At the Met Lab, he worked in the Purification and Metal Production Groups of Section C-I.
According to the Journal of Glenn T. Seaborg (Vol 2.), Jarret was transferred to Clinton Laboratories in Oak Ridge, TN on September 13, 1943 (p. 115). In his journal, Seaborg proposed that Jarrett should be a staff member in the Instrument and Physical Measurements Group at Oak Ridge. The section would be overseen by Spofford G. English and the group would be led by Casimer J. Borkowski. Robert L. Butenhoff and Jack D. East were also transferred to this group (p. 159)
For more information about the Jarrett and the personnel at the Met Lab, please see the following reference: