After August 1944, the implosion program began to engulf a growing fraction of the laboratory's personnel. Considerable research during the fall and following winter focused on experimental diagnostics. Seven parallel experimental programs – RaLa, betatron, magnetic, and electric pin studies, in addition to the original X-ray, photographic, and terminal observations – brought the most current techniques of experimental physics to bear on implosion problems. The foremost tasks were to determine the collapse time, compression, and symmetry, and to assess different explosives and explosive system designs. Informed trial and error was the approach most frequently taken in these simultaneous lines of experimental inquiry, since theoretical understanding was still incomplete. While each program offered its particular advantages, many efforts overlapped, adding modest confirmation to the amassing body of understanding. Despite lingering uncertainties about the feasibility of an implosion weapon, the six months following the August 1944 reorganization saw the central research question of the laboratory shift from “Can the implosion be built?” to “How can the implosion weapon be made?”

Much work also remained before plutonium components could be produced. In establishing a plutonium production system in the limited time available, the chemists and metallurgists, like the physicists, often relied on empirical methods guided by intuition, since little theory was available and methodical procedures were extremely time-consuming.

Experimental Diagnostics

The history of the seven-pronged experimental program to study implosion during World War II is one of painstaking progress, with few highlights or definitive measurements, many ambiguous steps, and numerous failures.