A meeting between J. Robert Oppenheimer, General Leslie Groves, George Kistiakowsky, James B. Conant, Richard Tolman, Hans Bethe, and Charles Lauritsen is held to fix the design approach for the plutonium bomb. It is agreed that work will focus on the solid core Christy gadget, use explosive lenses, use a modulated initiator, and electric detonators. The use of Composition B and Baratol for the lenses was also decided, as was the multiple lens configuration and detonator arrangement. However none of these approaches or components have been proved yet. Solid core compression has not been demonstrated at this time. A schedule for completing research, development, engineering, and testing is also established. The (partial) goals are:
- Solve detonator timing problem, have detonators in full production, and begin large-scale lens production (Apr 15).
- Begin hemisphere shots to measure shock wave convergence (Apr 25).
- Demonstrate implosion compression in full scale test (May 15).
- Begin lens fabrication for The Trinity Test (June 4).
- Begin assembly of The Trinity Test Gadget (July 4).