Comment by dboreham

Not sure they "discovered". Strictly speaking the Berkeley team first isolated, or produced Pu. Its theoretical existence had been known for a while prior (which is why they were trying to produce it). I mean, it wasn't that they were walking around and picked up and chunk and wondered what they had discovered. The project was entirely for the purpose of producing something every Nuclear Physicist knew must exist. They succeeded in making a small piece, which nobody had done successfully before.