Chung-Yao Chao
Born	(1902-06-27)27 June 1902 Zhuji, China
Died	28 May 1998(1998-05-28) (aged 95) Beijing, China
Alma mater	Southeast University National Central UniversityNanjing University California Institute of Technology
Known for	Seminal contributions to the discovery ofantimatter
Scientific career
Fields	Physics
Institutions	Southeast University National Central University Nanjing University National Southwestern Associated University University of Science and Technology of China

Chung-Yao Chao (Chinese:赵忠尧;pinyin:Zhào Zhōngyáo; 27 June 1902 – 28 May 1998) was a Chinese theoretical physicist. He studied the scattering ofgamma rays in lead bypair production in 1930, without knowing thatpositrons were involved in the anomalously high scattering cross-section. When the positron was discovered byCarl David Anderson in 1932, confirming the existence ofPaul Dirac's "antimatter", it became clear that positrons could explain Chung-Yao Chao's earlier experiments, with the gamma rays being emitted fromelectron-positron annihilation.

He enteredNanjing Higher Normal School (later renamedNational Southeastern University,National Central University andNanjing University), in 1920 and earned aBS inphysics in 1925. Then he earned aPhD degree in physics under supervision ofNobel Prize laureateRobert Andrews Millikan atCalifornia Institute of Technology in 1930. Later he went back to China and joined the physics faculty ofTsinghua University inBeijing.

The 1936Nobel Prize for Physics went toCarl D. Anderson for the discovery of the positron. While a graduate student at Caltech in 1930, Chao was the first to experimentally identifypositrons throughelectron–positron annihilation, but did not realize what they were. Anderson, Chao's classmate at Caltech, used the sameradioactive source,²⁰⁸
Tl, as Chao. (Historically,²⁰⁸
Tl was known as "thorium C double prime" or "ThC", seedecay chains.) Fifty years later, Anderson admitted that Chao had inspired his discovery: Chao's research formed the foundation from which much of Anderson's own work developed. Chao died in 1998, without sharing in a Nobel Prize acknowledgment.^[1]

• Wang, Zuoyue (1970–1980). "Zhao Zhongyao".Dictionary of Scientific Biography. Vol. 25. New York: Charles Scribner's Sons. pp. 397–402.ISBN 978-0-684-10114-9.

• 1902 births
• 1998 deaths
• Boxer Indemnity Scholarship recipients
• California Institute of Technology alumni
• Educators from Shaoxing
• Members of the Chinese Academy of Sciences
• Academic staff of the National Central University
• Physicists from Zhejiang
• Nanjing University alumni
• Academic staff of the National Southwestern Associated University
• Scientists from Shaoxing
• Academic staff of Tsinghua University
• Academic staff of the University of Science and Technology of China
• Academic staff of Yunnan University

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