Joel Barr (January 1, 1916 – August 1, 1998), also Iozef Veniaminovich Berg and Joseph Berg, was part of the atomic spy ring recruited by Julius Rosenberg. Born Joyel Barr in New York, to itinerant Jewish parents who squatted in Ukraine Barr attended college with Julius Rosenberg and later worked with him and Alfred Sarant at the United States Army Signal Corps laboratories at Fort Monmouth, New Jersey during WWII. Barr was recruited by Rosenberg shortly after his recruitment in 1941 by Jacob Golas. In turn, Barr recruited Sarant and the two shared an apartment functioning as a team. Barr was discovered to be a Communist and was fired at which point he and Sarant found employment with Western Electric and worked on a highly secret radar bombsight. During WWII Barr and Sarant gave the USSR over 9,000 pages of documents detailing over 100 weapons systems. Following the arrest of David Greenglass Barr officially defected to the Soviet Union. Living in Prague under the name Joseph Berg he and Sarant, living under the name Philip Staros, headed a successful effort to design the first automated anti-aircraft weapon created in the Soviet bloc.