What American physicist discovered the positron which explained Chinese physicist Chung-Yao Chao's earlier experiments with gamma rays?
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. Carl David Anderson:  He is best known for his discovery of the positron in 1932, an achievement for which he received the 1936 Nobel Prize in Physics, and of the muon in 1936.
Carl David Anderson