Rings of Earth: The Synchrotron

Abstract

In the valley of the beautiful Appalachian mountains of Tennessee, USA, on the banks of Clinch river, just 25 miles north of the famous Tennessee Valley Authority dam, a sleepy farming community came together to retaliate against the Japanese attack on Pearl Harbor. In 1943, thousands of scientists and engineers descended on this community, now named OakRidge, to work on Uranium enrichment, which would lead to the Manhattan project. Sir Marcus Oliphant, Ernest Lawrence’s trusted deputy, was one of them and was given the task of “watching the processes like an owl”. However, he must have found time for other things, because that is when he came up with the idea of holding the particles in a single orbit as in the Betatron, but accelerating the particles with an alternating voltage in a cavity, as in Wideroe’s concept, and wrote a memo to the Directorate of Atomic Energy, UK. In 1944, Vladimir Veksler of the Soviet Academy of Sciences in Moscow independently came up with a clearer idea, where the frequency of the voltage in the cavity would be varied, to take into account the relativistic reduction in orbital frequency at high particle energies. Before this paper was noticed in the West, Edwin McMillan of Lawrence Radiation Laboratory independently proposed a “synchrotron”, in which the magnetic field would be ramped as the energy increased to keep orbit radius same, but also the frequency of the radiofrequency source would be varied. He used the word “phase stability” to describe the physics behind it.