MIT Radiation Laboratory
The Radiation Laboratory was an American radar research laboratory operating during World War II at the Massachusetts Institute of Technology. Established in October 1940 after an exchange of Allied military secrets revealed the cavity magnetron to the United States, the lab focused principally on rapidly developing compact, microwave radar sets. It grew from thirty scientists to nearly 4,000 people at its peak, making it the largest contractor of the United States' Office of Scientific Research and Development and comparable in staffing to the main Los Alamos facility of the Manhattan Project.
The Rad Lab, as it was commonly called, designed approximately half of all radar systems deployed during World War II. Its systems included the SCR-584 gun-laying radar that destroyed 85 percent of V-1 flying bombs engaged over Britain; the airborne H2X radar that enabled American strategic bombing through clouds; and LORAN, the first worldwide radio navigation system. Unlike traditional research institutions, the Rad Lab conducted fundamental research, engineering development, "crash" production of experimental equipment, and field support in combat theaters. Most of its systems were built by industrial contractors; 48 percent of all American radar procurement, or $1.3 billion, was for equipment designed by the lab.
Lee DuBridge directed the laboratory, with Isidor Rabi overseeing research operations. The laboratory drew physicists and other researchers from sixty-nine universities and received $106.8 million in government contracts, dwarfing MIT's own academic budget and comprising 23 percent of all OSRD research spending. Though a civilian operation, the lab hosted offices and used facilities of both US military branches, and maintained close ties with its British military counterpart, the Telecommunications Research Establishment.
When it closed on December 31, 1945, its functions were dispersed to industry, new interdisciplinary laboratories within MIT, and in 1951, the newly formed Lincoln Laboratory. The 28-volume MIT Radiation Laboratory Series disclosed the lab's classified discoveries for postwar electronics development. Ten laboratory members later won Nobel Prizes, and its alumni and inventions helped establish Boston's Route 128 high-technology corridor. The lab's structure and its model of civilian-military scientific collaboration had lasting influence in postwar American science.
Origins
Pre-war radar development
During the 1930s, Britain, Germany, the United States, and other nations developed radio detection systems independently and under tight secrecy. Each country guarded its work as a potential war-winning advantage, unaware that rivals had reached similar capabilities. Germany fielded sophisticated systems earliest: the Freya early warning radar, Seetakt shipborne sets, and the Würzburg gun-laying radar. One historian judged German equipment "generally about a year ahead of the Americans." Britain established the first operational network, with Chain Home stations along its east coast providing aircraft detection at ranges exceeding 100 miles by 1939. More importantly, Britain developed an integrated system for directing fighter interceptors that no other nation matched. When British and American officials compared notes in September 1940, they discovered that their longwave systems were virtually identical: Chain Home Low and the US Navy's CXAM operated on the same frequency and shared key technical features.American radar development had split between two services with distinct priorities. The Naval Research Laboratory pursued detection on relatively long wavelengths, achieving the first American pulse radar detection of aircraft in December 1934 and installing production sets on capital ships by 1940. The Army Signal Corps, under Major William Blair, took a different path. Blair was convinced that the precision required for anti-aircraft fire demanded the narrow beams that only microwave wavelengths could provide, and he directed his laboratory at Fort Monmouth to concentrate on this approach. Using available microwave generators like the Barkhausen–Kurz tube and split-anode magnetron, Signal Corps researchers detected ships at 1,000 yards and vehicles at 250 feet, results far inferior to what the Navy obtained on longer wavelengths. By 1936, the effort had reached a dead end, and researchers reluctantly adopted the Navy's pulse techniques.
The advantages of microwaves were well understood by the British, German, and American programs: compact antennas that could fit in aircraft, narrow beams for precise tracking and clearer displays, and better detection of low-flying planes that slipped beneath longer-wavelength radars. But none had solved the fundamental problem of generating adequate power at centimeter wavelengths. The klystron, the most promising American generator, generated roughly one watt at ten centimeters, insufficient for practical radar.
American mobilization of civilian science
The outbreak of war in Europe in September 1939 prompted discussions among leading American scientists about organizing civilian researchers for national defense. Vannevar Bush, president of the Carnegie Institution, James Conant of Harvard, Karl Compton of MIT, and Frank B. Jewett of the National Academy of Sciences met repeatedly during the winter of 1939–1940 to consider how to bring American scientific and engineering talent to bear on military problems. In spring 1940, Britain sent physicist A. V. Hill to explore scientific cooperation with the United States and Canada, but Hill found his hands tied without authorization to disclose British secrets. He returned to London to press for formal exchange. The rapid German offensives in Norway and the Low Countries, followed by the fall of France in June, transformed these preliminary discussions into urgent action. As the Rad Lab's official historian observed, the collapse "shook Washington with only slightly less violence than London."Bush secured a fifteen-minute meeting with President Roosevelt on June 12, 1940, presenting a single-page proposal for a new agency to coordinate civilian research on military devices. Roosevelt approved immediately, and the National Defense Research Committee was established by executive order on June 27. Senior military leaders welcomed the initiative: Army Chief of Staff George C. Marshall told Bush that approaching war would force military laboratories to concentrate on procurement, leaving critical research gaps that NDRC could fill. The committee organized into five divisions, with Division D covering detection, controls, and instruments under Compton's direction.
Compton established a microwave section in mid-1940, headed by Alfred Loomis, a lawyer-turned-physicist who operated a private laboratory at Tuxedo Park where microwave experiments were already underway. The section, known as the Microwave Committee, included industry representatives from Bell Labs, General Electric, RCA, Westinghouse, and Sperry, as well as Ernest O. Lawrence from Berkeley. During summer 1940, committee members surveyed American radar efforts and concluded that microwave techniques offered significant potential, though they encountered the same fundamental obstacle British researchers had faced: the lack of a suitable high-power source.
The Tizard Mission
Unbeknown to the Americans, a research breakthrough had come in February 1940, when British physicists John Randall and Harry Boot at Birmingham University invented the resonant cavity magnetron. The new transmitter generated kilowatts of microwave power at ten-centimeter wavelengths, representing a thousandfold improvement over competing technologies like the klystron. By August 1940, British researchers had demonstrated the magnetron tracking aircraft in flight.The fall of France in June 1940 made Allied scientific interchange urgent. Before July was out, President Roosevelt approved an exchange of military secrets based on a diplomatic proposal from British Ambassador Lord Lothian. A British scientific mission headed by Henry Tizard, a university rector and scientific adviser to the Ministry of Aircraft Production, reached Washington in late August and early September 1940. The mission members brought a black box containing blueprints and technical data, with authorization to disclose any secret information the British government possessed in exchange for American secrets. Among their cargo was one of the Birmingham cavity magnetrons, which one official history later called "the most valuable cargo ever brought to our shores."
The mission arrived before the Army and Navy had authorized NDRC to disclose information to them. The Army granted permission on September 12, and the Navy, in more limited form, four days later. On September 19, Edward "Taffy" Bowen, a radar scientist from Britain's Telecommunications Research Establishment, demonstrated the magnetron to members of the Microwave Committee. Subsequent tests at Bell Telephone Laboratories confirmed the device generated approximately 15 kilowatts at 10-centimeter wavelength—far exceeding any American microwave source. On September 28–29, members of the British mission joined the Microwave Committee as guests of Loomis at Tuxedo Park, where they established priorities for microwave radar development: airborne interception radar for night fighters was designated the most urgent task.
Laboratory establishment
The committee concluded that exploiting the magnetron required a dedicated central laboratory staffed by research physicists. Initial plans to locate the facility at Bolling Field in Washington encountered delays. It became clear that NDRC lacked authority to operate laboratories directly, but could contract with existing institutions. Independent surveys by Bush and the Microwave Committee both identified MIT as the institution best positioned to provide the necessary space, scientific staff, and capacity for rapid expansion. On October 17, 1940, they secured Compton's agreement to host the laboratory at MIT, though Compton had reservations and recused himself from the formal decision.NDRC's Steering Committee approved the contract on October 25, 1940, with initial funding of $455,000. The laboratory was named "Radiation Laboratory," a title selected to suggest similarity to Ernest Lawrence's nuclear physics facility at Berkeley rather than reveal its radar mission. Recruitment began immediately, drawing primarily on nuclear physicists familiar with high-frequency techniques from accelerator work. Lawrence declined the directorship but used his extensive network to recruit researchers, including Kenneth Bainbridge from Harvard and Lee DuBridge from the University of Rochester, whom NDRC appointed as director.
In late October 1940, approximately 600 scientists gathered in Boston for a conference on applied nuclear physics. Loomis and Bowles organized laboratory visits and special seminars on microwave techniques. At an October 30 luncheon at the Algonquin Club, Loomis and Compton briefed about two dozen recruits who signed secrecy agreements before receiving details on the laboratory's mission. Within weeks, the effort had attracted Isidor Rabi from Columbia, who brought students Jerrold Zacharias and Norman Ramsey, as well as Luis Alvarez and Edwin McMillan from Berkeley. On November 11, 1940, the laboratory held its first group meeting in Room 4-133 on the MIT campus, a secure 10,000-square-foot space surrounded by the institute's electrical engineering program. By mid-December, approximately 30 physicists were at work, and a wooden penthouse laboratory had been erected on the roof of Building 6.