Lauritsen was born in
Holstebro, Denmark and studied
architecture at the Odense Tekniske Skole, graduating in 1911. In 1916 he emigrated to the
United States with his wife Sigrid Henriksen and son Tommy, first to Florida, where the family lived for a time on a houseboat, and later to Boston, where he worked as a draftsman during the
Great War and was a witness to the
Boston Molasses Disaster. By 1921, he was working in
Palo Alto on radio for communicating between ship and shore. He became interested in the design of
radio receivers, and for a few months in 1922 was in business with two partners building radios. By 1923, he had moved to
St. Louis where he was chief engineer at the Kennedy Corporation, a producer of consumer radio receivers. In 1926, Lauritsen attended a public lecture by
Robert Millikan who, in casual conversation afterwards, invited him to visit
Caltech. Lauritsen and his family soon moved to
Pasadena where he talked his way into graduate study in physics. In 1929, he received his
Ph.D., and, in 1930, he joined the physics department faculty. He spent the remainder of his academic career as professor of physics at this institution, finally retiring in 1962. In 1928, he and Ralph D. Bennett developed
X-ray tubes of exceptionally high voltage. These tubes were then used for radiation therapy of
cancer patients in the Kellogg Radiation Laboratory, built as a treatment clinic in 1931. Sigrid Lauritsen, who was one of the first female graduates of the
University of Southern California medical school, worked in the clinic as a radiologist. In 1932, he converted one of his X-ray tubes into an accelerator of protons and helium ions and began to study nuclear reactions. In 1934, Lauritsen and H. Richard Crane used a sample of recently discovered
deuterium, obtained from G.N. Lewis at Berkeley, to generate
neutrons with which they made the first accelerator-produced artificial radioactivity. He later measured the radiation produced when a
positron and an
electron annihilate each other. One of his most significant discoveries was to show that protons could be captured by a
carbon nucleus, releasing
gamma rays. This radiative capture process was applied to the study of the nuclear processes at the heart of a
star, and the production of the heavier elements. In 1939, the laboratory ceased to do medical therapy and concentrated on nuclear physics. (Lauritsen was director of the laboratory from its inception until he retired in 1962.) In 1937, he invented a radiation detector called the Lauritsen electroscope, widely used as
quartz fiber radiation dosimeters. ==Weapons development==