Carbon dating inventor
Although doubts remained, construction work began on the K-25 full-scale production plant in September 1943. Tests began on the machinery at K-25 in April 1944 without a barrier.
A man called Willard F Libby pioneered it at the University of Chicago in the 50's. This is now the most widely used method of age estimation in the field of archaeology.
He also developed sensitive radiation detectors that could use the technique.
Tests against sequoia with known dates from their tree rings showed radiocarbon dating to be reliable and accurate.
The SAM Laboratories therefore had to find a way of separating kilograms of it from the more abundant uranium-238.
Gaseous diffusion worked on the principle that a lighter gas diffuses through a barrier faster than a heavier one at a rate inversely proportional to its molecular weight.
The technique revolutionised archaeology, palaeontology and other disciplines that dealt with ancient artefacts.