Chung-Yao Chao
When the positron was discovered by Carl David Anderson in 1932, confirming the existence of Paul Dirac's "antimatter", it became clear that positrons could explain Chung-Yao Chao's earlier experiments, with the gamma rays being emitted from electron-positron annihilation.Then he earned a PhD degree in physics under supervision of Nobel Prize laureate Robert Andrews Millikan at California Institute of Technology in 1930.Later he went back to China and joined the physics faculty of Tsinghua University in Beijing.While a graduate student at Caltech in 1930, Chao was the first to experimentally identify positrons through electron–positron annihilation, but did not realize what they were.(Historically, 208Tl was known as "thorium C double prime" or "ThC", see decay chains.)