 It had been observed in Britain by Frisch and Titterton, and independently in the Soviet Union by Georgy Flyorov and Konstantin Petrzhak in 1940; the latter are generally credited with the discovery.Compton had also heard from the French physicist Pierre Auger that Frédéric Joliot-Curie had detected what might have been spontaneous fission in polonium.If true, it might preclude the use of polonium in the neutron initiators; if true for plutonium, it might mean that the gun-type design would not work.