Chung-Yao Chao (; 27 June 1902 – 28 May 1998) was a Chinese theoretical physicist. He studied the scattering of

gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...

s in lead by pair production in 1930, without knowing that

positron The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 '' e'', a spin of 1/2 (the same as the electron), and the same mass as an electron. When a positron collide ...

s were involved in the anomalously high scattering cross-section. When the positron was discovered by Carl David Anderson in 1932, confirming the existence of

Paul Dirac Paul Adrien Maurice Dirac (; 8 August 1902 – 20 October 1984) was an English theoretical physicist who is regarded as one of the most significant physicists of the 20th century. He was the Lucasian Professor of Mathematics at the Univer ...

's "

antimatter In modern physics, antimatter is defined as matter composed of the antiparticles (or "partners") of the corresponding particles in "ordinary" matter. Antimatter occurs in natural processes like cosmic ray collisions and some types of radioac ...

", it became clear that positrons could explain Chung-Yao Chao's earlier experiments, with the gamma rays being emitted from electron-positron annihilation. He entered Nanjing Higher Normal School (later renamed

National Southeastern University Nanjing University (NJU; ) is a national public research university in Nanjing, Jiangsu. It is a member of C9 League and a Class A Double First Class University designated by the Chinese central government. NJU has two main campuses: the Xi ...

National Central University National Central University (NCU, ; Pha̍k-fa-sṳ: ''Kwet-li̍p Chung-yong Thài-ho̍k'', Wade–Giles: ''Kuo2 Li4 Chung Yang Ta4 Hsüeh2'' or ''中大'', ''Chung-ta'') is a public research university with long-standing traditions based in Taiw ...

and

Nanjing University Nanjing University (NJU; ) is a national public research university in Nanjing, Jiangsu. It is a member of C9 League and a Class A Double First Class University designated by the Chinese central government. NJU has two main campuses: the Xian ...

), in 1920 and earned a BS in

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...

in 1925. Then he earned a

PhD PHD or PhD may refer to: * Doctor of Philosophy (PhD), an academic qualification Entertainment * '' PhD: Phantasy Degree'', a Korean comic series * '' Piled Higher and Deeper'', a web comic * Ph.D. (band), a 1980s British group ** Ph.D. (Ph.D. al ...

degree in physics under supervision of

Nobel Prize laureate The Nobel Prizes ( sv, Nobelpriset, no, Nobelprisen) are awarded annually by the Royal Swedish Academy of Sciences, the Swedish Academy, the Karolinska Institutet, and the Norwegian Nobel Committee to individuals and organizations who make out ...

Robert Andrews Millikan Robert Andrews Millikan (March 22, 1868 – December 19, 1953) was an American experimental physicist honored with the Nobel Prize for Physics in 1923 for the measurement of the elementary electric charge and for his work on the photoelectric ...

California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

in 1930. Later he went back to China and joined the physics faculty of

Tsinghua University Tsinghua University (; abbr. THU) is a national public research university in Beijing, China. The university is funded by the Ministry of Education. The university is a member of the C9 League, Double First Class University Plan, Projec ...

Beijing } Beijing ( ; ; ), Chinese postal romanization, alternatively romanized as Peking ( ), is the Capital city, capital of the China, People's Republic of China. It is the center of power and development of the country. Beijing is the world's Li ...

Nobel Prize controversy

The 1936

Nobel Prize for Physics ) , image = Nobel Prize.png , alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...

went to

Carl D. Anderson Carl David Anderson (September 3, 1905 – January 11, 1991) was an American physicist. 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. ...

for the discovery of the positron. While a graduate student at Caltech in 1930, Chao was the first to experimentally identify

s through

electron–positron annihilation Electron–positron annihilation occurs when an electron () and a positron (, the electron's antiparticle) collide. At low energies, the result of the collision is the annihilation of the electron and positron, and the creation of energetic photo ...

, but did not realize what they were. Anderson, Chao's classmate at Caltech, used the same

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...

source, , as Chao. (Historically, was known as "thorium C double prime" or "ThC", see

decay chain In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". Most radioisotopes do not decay dire ...

s.) 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.

Nobel Prize controversy

References

Further reading