Rutherford and others, Oliphant thereby discovered the nuclei of helium-3 (helions) and tritium (tritons). Oliphant used electromagnetic separation to separate the isotopes of lithium. He was the first to experimentally demonstrate nuclear fusion. He found that when deuterons reacted with nuclei of helium-3, tritium or with other deuterons, the particles that were released had far more energy than they started with. Binding energy had been liberated from inside the nucleus. Following Arthur Eddington's 1920 prediction that energy released by fusing small nuclei together could provide the energy source that powers the stars, Oliphant speculated that nuclear fusion reactions might be what powered the sun. With its higher cross section, the deuterium–tritium nuclear fusion reaction became the basis of a hydrogen bomb. Oliphant had not foreseen this development: In 1934, Cockcroft arranged for Oliphant to become a fellow of St John's College, Cambridge, which paid about £600 a year. When Chadwick left the Cavendish Laboratory for the University of Liverpool in 1935, Oliphant and Ellis both replaced him as Rutherford's assistant director for research. The job came with a salary of £600 (). With the money from St John's, this gave him a comfortable income. Oliphant soon fitted out a new accelerator laboratory with a 1.23 MeV generator at a cost of £6,000 () while he designed an even larger 2 MeV generator. He was the first to conceive of the proton synchrotron, a new type of cyclic particle accelerator. In 1937, he was elected to the Royal Society. When he died he was its longest-serving fellow. University of Birmingham Samuel Walter Johnson Smith's imminent mandatory retirement at age 65 prompted a search for a new Poynting Professor of Physics at the University of Birmingham. The university wanted not just a replacement, but a well-known name, and was willing to spend lavishly in order to build up nuclear physics expertise at Birmingham. Neville Moss, its Professor of Mining Engineering and the Dean of its Faculty of Science approached Oliphant, who presented his terms. In addition to his salary of £1,300 (), he wanted the university to spend £2,000 () to upgrade the laboratory, and another £1,000 per annum () on it. And he did not wish to start until October 1937, to enable him to wrap up his work at the Cavendish Laboratory. Moss agreed to Oliphant's terms. To obtain funding for the cyclotron that he wanted, Oliphant wrote to the