60-inch cyclotron, 1939. This shows the cyclotron at the Lawrence Radiation Laboratory, Berkeley, soon after completion in 1939. The key figures in its development and use are shown, standing, left to right: Dr D Cooksey, Dr D Corson, Dr Ernest Orlando Lawrence (1901-58), the inventor of the cyclotron; Dr R Thornton, Dr J Backus, WS Sainsbury, Dr LW Alvarez (1911-88) and Dr Edwin Mattison McMillan (1907-1991). By Science Museum London / Science and Society Picture Library [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0/deed.en)], via Wikipedia

https://en.wikipedia.org/wiki/File:60-inch_cyclotron,_c_1930s._This_shows_the_(9660569583).jpg