Poltergeist project

When in 1956, two Américans physicists Cowan et Reines, proved that the neutrino was a real particle, its existence was admitted, but it was considered « undetectable ».

It was in the mid 1950s that Clyde Cowan and Frederick Reines set up their experiment to prove the existence of neutrinos. Reines and Cowan started their neutrino detection experiment with a reactor at Hanford in Washington State. Then they moved to a new, more powerful reactor at Savannah River in South Carolina. That was the time also when the first nuclear reactors for civilian use were put into operation. Cowan and Reines had the idea to take advantage of the intense flux of neutrinos they generated, fluxes ranging from 1000 to 10,000 billion neutrinos per second and square centimetre, much more intense than those expected from radioactive sources. This pioneering experience, they was called the Poltergeist project, definitely proved the existence of the neutrino and opened the way for neutrino physics.


Reines joined the then-secret lab in Los Alamos in 1944 to help create the world’s first atomic bombs. He worked under famed physicists Richard Feynman and Hans Bethe.

By 1947, Reines first thought of pursuing evidence for neutrinos (a subatomic particle with no electric charge and a very small mass), which prompted him to ask for a sabbatical-in-residence. Decades later, he recalled, “In 1951, following the [nuclear] tests in Eniwetok Atoll in the Pacific, I decided I really would like to do some fundamental physics. … I moved to a stark empty office, staring at a blank pad for several months searching for a meaningful question worthy of a life’s work. The months passed and all I could dredge up out of the subconscious was the possible utility of a bomb for the direct detection of neutrinos.”