before much energy has been released. It was decided to use a nearly critical sphere of plutonium and compress it quickly by explosives into a much smaller and denser core, a technical challenge at the time. To create the symmetrical implosion required to compress the plutonium core to the required density, thirty-two explosive charges were to be simultaneously detonated around the spherical core. Using conventional explosive techniques with blasting caps, progress towards achieving simultaneity to within a small fraction of a microsecond was discouraging. Alvarez directed his graduate student, Lawrence H. Johnston, to use a large capacitor to deliver a high voltage charge directly to each explosive lens, replacing blasting caps with exploding-bridgewire detonators. The exploding wire detonated the thirty-two charges to within a few tenths of a microsecond. The invention was critical to the success of the implosion-type nuclear weapon. He also supervised the RaLa Experiments. Alvarez later wrote that: Again working with Johnston, Alvarez's last task for the Manhattan Project was to develop a set of calibrated microphone/transmitters to be parachuted from an aircraft to measure the strength of the blast wave from the atomic explosion, so as to allow the scientists to calculate the bomb's energy. After being commissioned as a lieutenant colonel in the United States Army, he observed the Trinity nuclear test from a B-29 Superfortress that also carried fellow Project Alberta members Harold Agnew and Deak Parsons (who were respectively commissioned at the rank of captain). Flying in the B-29 Superfortress The Great Artiste in formation with the Enola Gay, Alvarez and Johnston measured the blast effect of the Little Boy bomb which was dropped on Hiroshima. A few days later, again flying in The Great Artiste, Johnston used the same equipment to measure the strength of the Nagasaki explosion. Bubble chamber Returning to the University of California, Berkeley as a full professor, Alvarez had many ideas about how to use his wartime radar knowledge to improve particle accelerators. Though some of these were to bear fruit, the "big idea" of this time would come from Edwin McMillan with his concept of phase stability which led to the synchrocyclotron. Refining and extending this concept, the Lawrence team would build the world's then-largest proton accelerator, the Bevatron, which began operating in 1954. Though the Bevatron could produce copious amounts of interesting particles, particularly in secondary collisions, these complex interactions were hard to detect and analyze