Carl David Anderson

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Carl David Anderson
Carl anderson.1937.jpg
Carl Anderson at LBNL, 1937
Born (1905-09-03)September 3, 1905
New York City, New York, USA
Died January 11, 1991(1991-01-11) (aged 85)
San Marino, California, USA
Nationality United States
Fields Physics
Institutions California Institute of Technology
Alma mater California Institute of Technology
Notable students Donald A. Glaser</br>Seth Neddermeyer
Known for Discovery of the positron</br>Discovery of the muon
Notable awards Nobel Prize in Physics 1936
Elliott Cresson Medal (1937)

Carl David Anderson (3 September 1905 – 11 January 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.


Anderson was born in New York City, the son of Swedish immigrants. He studied physics and engineering at Caltech (B.S., 1927; Ph.D., 1930). Under the supervision of Robert A. Millikan, he began investigations into cosmic rays during the course of which he encountered unexpected particle tracks in his cloud chamber photographs that he correctly interpreted as having been created by a particle with the same mass as the electron, but with opposite electrical charge. This discovery, announced in 1932 and later confirmed by others, validated Paul Dirac's theoretical prediction of the existence of the positron. Anderson obtained the first direct proof that positrons existed by shooting gamma rays produced by the natural radioactive nuclide ThC'' (208Tl)[1] into other materials, resulting in creation of positron-electron pairs. For this work, Anderson shared the Nobel Prize in Physics for 1936 with Victor Hess.[2]

Also in 1936, Anderson and his first graduate student, Seth Neddermeyer, discovered the muon (or 'mu-meson', as it was known for many years), a subatomic particle 207 times more massive than the electron. Anderson and Neddermeyer at first believed that they had seen the pion, a particle which Hideki Yukawa had postulated in his theory of the strong interaction. When it became clear that what Anderson had seen was not the pion, the physicist I. I. Rabi, puzzled as to how the unexpected discovery could fit into any logical scheme of particle physics, quizzically asked "Who ordered that?" (sometimes the story goes that he was dining with colleagues at a Chinese restaurant at the time). The muon was the first of a long list of subatomic particles whose discovery initially baffled theoreticians who could not make the confusing "zoo" fit into some tidy conceptual scheme. Willis Lamb, in his 1955 Nobel Prize Lecture, joked that he had heard it said that "the finder of a new elementary particle used to be rewarded by a Nobel Prize, but such a discovery now ought to be punished by a 10,000 dollar fine." [3]

Anderson spent all of his academic and research career at Caltech. During World War II, he conducted research in rocketry there. He was elected a Fellow of the American Academy of Arts and Sciences in 1950.[4] He died on January 11, 1991, and his remains were interred in the Forest Lawn, Hollywood Hills Cemetery in Los Angeles, California.



  1. ThC" is a historical designation of 208Tl, see Decay chains
  2. Physics 1936
  4. "Book of Members, 1780-2010: Chapter A" (PDF). American Academy of Arts and Sciences. Retrieved 17 April 2011. 

External links