John Alexander Simpson

John Alexander Simpson (November 3, 1916 – August 31, 2000) was an American physicist and science educator. He was deeply committed to educating the public and political leaders about science and its implications, most notably as a principal founder of the Bulletin of the Atomic Scientists and a long-time member of the organization's board of sponsors.

He is known for inventions such as the gas flow α-particle proportional counter (for measuring plutonium yields in the presence of high intensity fission products), and the neutron monitor,

Simpson spent his career as an instructor and researcher for the University of Chicago's Enrico Fermi Institute and Department of Physics, where he conducted experiments in nuclear physics and with cosmic rays. His research continued up until a few weeks prior to his death.

Early life Born in Portland, Oregon, Simpson was an accomplished clarinetist and saxophonist in his early years, receiving an award in high school for his virtuosity. He obtained an MS from New York University in 1943, and a Ph.D. a year later. It was at New York University in 1943 when Simpson was invited to be employed at University of Chicago. Volney Wilson, an administrator at the university's Metallurgical Laboratory asked him to help invent instruments for measuring high levels of radioactivity. It took much convincing, but Simpson finally agreed to help. He was also a co-founder that same year of the Bulletin of the Atomic Scientists. The bulletin's aim was to spell out the implications of the atomic bomb and provide rational courses of action in response to the implications. Nancy Farley Wood worked with Simpson and is credited with the development and production of the radiation detectors for the laboratory.

Simpson was a pioneer in the study of cosmic rays. Beginning in 1946 with investigations into cosmic ray neutrons in the lower atmosphere (developed from pre-World War II work by Serge Korff), he contributed significantly throughout the years to the field's development with his scientific investigations. The instrument involved a thin sheet of plastic that was polymerized in the presence of a strong electric field perpendicular to the plane of the plastic, and then electrically polarized carrying a positive electric charge on one of its surfaces and a negative charge on the other. When a dust particle or heavy nucleus penetrated the sheet, it vaporized a small area, releasing the charges on the sheet and creating an electrical signal which indicated the location and size of the hole in the plastic; precise calibration allowed information about the collision, such as particle speed and size, to be extracted from the signal. These calibrations took place from 1985 until 1989. This device was used on Vega 1 and Vega 2 spacecraft to Halley's Comet in 1986, and earned him the Gagarin Medal for Space Exploration that year for his contribution towards the success of the Vega mission, as his instruments had been the only ones from the United States to encounter the comet. In 1999, he was awarded the Leo Szilard Lectureship Award for his role in educating scientists, members of the United States Congress, and the public on the importance of civilian control of nuclear policy and his critical efforts in planning and execution of the International Geophysical Year and the Ó Ceallaigh Medal for contributions to cosmic ray physics. Simpson has also provided lectures to the public using funds in 1974 which came from his Compton Chair in an attempt to reach a larger audience with his research. In 1982, he also established and became the first chairman of the Universities Space Science Working Group in Washington, D.C., in order to represent the space science laboratories in their dealings with the US Congress and NASA.