Chien-Shiung Wu, with colleagues Y. K. Lee and L. W. Mo, who confirmed the theory of conservation of vector current in 1963. In the experiments, which took several months to complete, proton beams from Columbia University’s Van de Graaff accelerator were transmitted through pipes to strike a 2 mm boron target at the entrance to a spectrometer chamber. Smithsonian Institution Archives, Accession 90-105, Science Service Records, Image No. SIA2010-1508