Anderson, Carl D. (Carl David), 1905-1991

Physicist.

Epithet: of George G. Harrap, publishers

Anderson (1905-1991). Physicist, California Institute of Technology.

Anderson, Carl David, 1905-1991.

Biography

Carl David Anderson was born September 3, 1905, in New York City. He was the only child of Swedish immigrants Carl David Anderson and Emma Adolfina Ajaxson. In 1912 the family moved to Los Angeles, where the elder Anderson managed a small restaurant business. Carl attended Los Angeles Polytechnic High School, from which he graduated in 1923. The following fall he entered the California Institute of Technology in Pasadena as a freshman, intending to study electrical engineering. In his sophomore year, during a course with Ira Bowen, he decided to change his major to physics. After receiving his BS in 1927, he stayed on at Caltech to do graduate work under Robert A. Millikan. His doctoral thesis, entitled "Space-Distribution of X-Ray Photoelectrons Ejected from the K and L Atomic Energy-Levels," involved a cloud-chamber study of photoelectrons (electrons exposed to radiation) scattered from various gases by X rays. He received his PhD in 1930.

Anderson was encouraged by Millikan to stay on at Caltech for a postdoctoral year to conduct experimental research on the penetrating radiation known as cosmic rays. Anderson designed and constructed an apparatus consisting of a giant electromagnet wrapped around a cloud chamber. He inserted a lead plate into the middle of the cloud chamber to lessen the particles' energy and to clarify the direction of their motion (negatively charged particles moved downward). An arc-lighted camera was focused on the chamber's window to record the vapor trails of electrons or other charged particles passing through. The magnet cloud chamber was put in operation in October 1931. At this time, scientists had only identified two elementary particles of matter--the electron and the proton. However, in 1928 Paul Dirac, in what came to be known as Dirac's equations, posited the existence of another particle, comparable in mass to the negatively charged electron, but with a positive charge, an "anti-electron." On August 2, 1932, viewing a very clear photograph of an upward-moving particle with mass similar to the electron, Anderson knew he had discovered the "positive electron," later named the positron. This was the particle predicted by Dirac. In fact, Dirac's theory predicted that all elementary particles should have their own antiparticles. Thus the term "antimatter" emerged, and Anderson was hailed as its discoverer. Anderson published his research in Science magazine on September 9, 1932. At first his results were met with skepticism. Ultimately they were confirmed by experimenters, initially in 1933 at the Cavendish Laboratory in Cambridge, England, by Patrick M. S. Blackett and G. P. S. Occhialini.

Anderson's work garnered him the Nobel Prize in 1936, at the age of only 31. A year prior to this date, in 1935, Anderson and his first graduate student, Seth Neddermeyer, discovered another subatomic particle, which they named the mesotron (later called the μ-meson or muon). The muon discovery grew out of experimental work on cosmic rays done at high altitude (around 14,000 feet) on Pikes Peak in Colorado. In 1933 Anderson became assistant professor at Caltech. He was named associate professor in 1937 and professor in 1939.

During World War II Anderson was closely associated with the Caltech rocket research and development effort, led by Charles C. Lauritsen and funded by the U. S. Office of Scientific Research and Development (OSRD). Anderson spent his time working on problems associated with the launching of rockets from airplanes. For his wartime work, he received the Presidential Certificate of Merit in 1945. In 1946 Anderson married Lorraine Bergman. They had two sons.

In the postwar period Anderson returned to his work on cosmic rays. He and his graduate students continued to take cloud chamber photographs at high altitudes, now using a B-29 aircraft, and also measuring variations in cosmic-ray effects at selected latitudes on the Earth's surface. They painstakingly accumulated further evidence of the existence of more subatomic particles, thus confirming the underlying complexity in the structure of matter and leading the way to a new branch of study, particle physics.

By the late 1950s, Anderson's kind of cosmic-ray investigation was beginning to be supplanted by work done on huge high-energy accelerators, both at Caltech and around the world. Anderson became chairman of the Caltech's Division of Physics, Mathematics and Astronomy in 1962, a position which he held until 1970. He retired from Caltech in 1976 with the title Board of Trustees Professor of Physics, Emeritus.

In addition to the Nobel Prize, Anderson was the recipient of many awards: the Gold Medal of the American Institute of the City of New York (1935), the Elliott Cresson Medal of the Franklin Institute (1937), the John Erikson Medal of the American Society of Swedish Engineers (1960), in addition to three honorary doctorates from Colgate University (1937), Temple University (1949) and Gustavus Adolphus College (1963). He was elected to the National Academy of Sciences in 1936 and to the American Academy of Arts and Sciences in 1954. Anderson died in San Marino, California, at the age of 85.