Carl David Anderson

For other people named Carl Anderson, see Carl Anderson (disambiguation).

Carl David Anderson (September 3, 1905 – January 11, 1991) was an American particle physicist who shared the 1936 Nobel Prize in Physics with Victor Hess "for his discovery of the positron".

Carl Anderson
Born	(1905-09-03)September 3, 1905 New York City, US
Died	January 11, 1991(1991-01-11) (aged 85) San Marino, California, US
Resting place	Forest Lawn Memorial Park, Hollywood Hills
Alma mater	California Institute of Technology (BS, PhD)
Known for	Discovering the positron (1932) Discovering the muon (1936)
Spouse	Lorraine Bergman ​ (m. 1946)​
Children	2
Awards	Nobel Prize in Physics (1936) Elliott Cresson Medal (1937) Membership of NAS (1938)
Scientific career
Fields	Particle physics
Institutions	California Institute of Technology
Thesis	Space-Distribution of X-ray Photoelectrons Ejected from the K and L Atomic Energy-Levels  (1930)
Doctoral advisor	Robert Millikan
Doctoral students	Seth Neddermeyer (1935) Leon Katz (1943)[1] James C. Fletcher (1948)[1] Donald Glaser (1950)[1] George Trilling (1955)[1] Carl A. Rouse (1956)[1]

Early life

Carl David Anderson was born on September 3, 1905, in New York City, to Swedish immigrants, Carl David Anderson Sr. and Emma Adolfina Ajaxson.

Anderson studied physics and engineering at Caltech, receiving his B.S. in 1927 and his Ph.D. in 1930.

Research

Discovery of the positron

Under the supervision of Robert Millikan, Anderson began investigations into cosmic rays during the course of which he encountered unexpected particle tracks in his (modern versions now commonly referred to as an Anderson) cloud chamber photographs that he correctly interpreted as having been created by a particle with the same mass as the electron, but with opposite electric charge.

Photo by Anderson of the first positron ever observed, 15 March 1933

This discovery, announced in 1932 and later confirmed by others, validated Paul Dirac's theoretical prediction of the existence of the positron. Anderson first detected the particles in cosmic rays. He then produced more conclusive proof by shooting gamma rays produced by the natural radioactive nuclide ThC'' (²⁰⁸Tl)^[2] into other materials, resulting in the creation of positron-electron pairs.

For this work, Anderson shared the 1936 Nobel Prize in Physics with Victor Hess.^[3] Fifty years later, Anderson acknowledged that his discovery was inspired by the work of his Caltech classmate, Chung-Yao Chao, whose research formed the foundation from which much of Anderson's work developed but was not credited at the time.^[4]

Discovery of the muon

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, but with the same negative electric charge and spin 1/2 as the electron, again in cosmic rays.

Anderson and Neddermeyer at first believed that they had seen a 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."^[5]

Personal life and death

In 1946, Anderson married Lorraine Bergman, with whom he had two sons.^[6]

Anderson died on January 11, 1991, in San Marino, California, at the age of 85. His remains were interred at the Forest Lawn Memorial Park in Los Angeles, California.

Awards

Anderson was elected to the National Academy of Sciences and the American Philosophical Society in 1938.^[7][8] He was elected a Fellow of the American Academy of Arts and Sciences in 1950.^[9] He received the Elliott Cresson Medal of the Franklin Institute in 1937 and the Golden Plate Award of the American Academy of Achievement in 1975.^[10]

Select publications

• Anderson, C. D. (1933). "The Positive Electron". Physical Review. 43 (6): 491–494. Bibcode:1933PhRv...43..491A. doi:10.1103/PhysRev.43.491.
• Anderson, C. D. (1932). "The Apparent Existence of Easily Deflectable Positives". Science. 76 (1967): 238–9. Bibcode:1932Sci....76..238A. doi:10.1126/science.76.1967.238. PMID 17731542.
• Anderson, C. D. (technical advisor) (1957). The Strange Case of the Cosmic Rays. The Bell Laboratory Science Series.