in 1959, rafter was appointed the inaugural director of the dsir’s institute of nuclear sciences, in gracefield, new zealand. in his new position, rafter encouraged research into natural variations in radiocarbon levels, in the process discovering a link between atmospheric nuclear weapons tests and rising levels of radiocarbon in the atmosphere, a phenomenon he and fergusson called the ‘atom bomb effect’ when they published their results in 1957. rafter also encouraged the use of naturally occurring stable (non-radioactive) isotopes for geological research, developing techniques for use in geothermal and environmental studies.