Paul Clarence Aebersold, nuclear physicist, authority on and proponent of the peaceful use of atomic energy, and U.S. Atomic Energy Commission official widely acclaimed as "Mr. Isotope," was born in Fresno, California on July 7, 1910, the son of Paul and Dora Houck Aebersold. An early interest in science was nourished through reading science and science fiction magazines and experiments such as the building of a crystal radio at age 12. This interest continued to grow and, following graduation from Oakland High School, led to enrollment at Pasadena Junior College and subsequently at Stanford University.

Upon receiving a B.A. in Physics, cum laude, from Stanford in 1932, Mr. Aebersold enrolled at the University of California at Berkeley for graduate study. His interest and excellence in track first led him to go to Berkeley, the site of the 1932 Olympic tryouts. Mr. Aebersold was aware of Ernest O. Lawrence's work on the cyclotron and decided to visit him during the Olympic trials. He found Lawrence at work repairing a leak in the vacuum chamber and immediately became involved in the repairs. Thus, what was originally intended as a ten-minute visit turned into a stay of ten years, first as a graduate student and then as a teacher and research scientist.

Mr. Aebersold was awarded an M.A. in Physics by the University of California in 1934 and immediately began his doctoral studies at the same school. Employment applications and biographical sketches consistently report that Mr. Aebersold received his Ph. D. in nuclear and medical physics in 1938, however, this date is subject to question. The printed program for Dr. Aebersold's final examination is dated May 11, 1939. The papers also contain three photographs of Dr. Aebersold in cap and gown which are dated May 19 and 20, 1939. the title of Dr. Aebersold's dissertation is "The Collimation of Fast Neutrons."

While a graduate student at the University of California, Dr. Aebersold held a position as Teaching Assistant in Physics and was awarded fellowships by the Christine-Breon Fund and the Finney-Howell Foundation. both of the latter involved research projects in the Radiation Laboratory. Following his graduation, he remained at the Laboratory until 1942. During his ten years in Berkeley, Dr. Aebersold participated in the developments of the 27, 60, and 184-inch cyclotrons. For the last two years, he was in charge of the operation of the 60-inch cyclotron.

Early in 1942, the Radiation Laboratory changed its emphasis from peaceful to wartime activities and entered upon an official program with the OSRD to obtain enriched U 235. At that time Dr. Aebersold became a special administrative aid to Dr. Ernest O. Lawrence and assisted in the coordination of research, personnel, security, and administrative phases of the growth of the Laboratory staff from about 20 to over 1, 000 members. During 1943, Dr. Aebersold served as head of the Information Division of the Radiation Laboratory and was charged with obtaining the latest information on experiments and on operation experience with the pilot separation equipment at Berkeley and with seeing that the information was properly communicated to the Y-12 plant at Oak Ridge. He was also involved in the filing of patents on the Berkeley developments and the growing concern over the health and safety problems involved in experiments with atomic energy.

In June 1944, Dr. Aebersold was transferred to Oakridge where he served in the Research Control Division of the District Engineer's Office. Here he was involved in the liaison between and inspection of various secret phases of research, health and safety problems, and information dissemination. The following June, Dr. Aebersold was sent to Los Alamos to assist in the health problems in connection with the atomic bomb test. He participated in the protection of personnel during the assembling and testing of the bomb and made extensive radiation measurements after the test.

The end of World War II brought about a return of emphasis upon peaceful uses of atomic energy. From February 1946, when he became Chief of the Isotopes Branch at Oak Ridge, until his retirement in 1965, Dr. Aebersold was at the forefront of this activity. From 1946 until 1957, Dr. Aebersold remained at Oak Ridge serving variously as Chief of the Isotopes Branch of the Research Division, 1946-1947; Chief of the Isotopes Division, 1947-1952; Director of the Isotopes Division, 1952-1956; and Director of the Isotopes Extension, 1956-1957. In April of the latter year, he was transferred to Washington to fill the newly created position of Assistant Director for Isotopes and Radiation in the division of Civilian Application. A year and a half later, he was advanced to Director of the Office of Isotopes Development. In 1961, Dr. Aebersold became Director of the Division of Isotopes Development, the position he held at the time of his retirement in 1965.

Since he entered into the field of isotope production and distribution at such an early stage, Dr. Aebersold was involved in finding solutions to a great many problems in the areas of production, radiation safety, regulation and training of users. He was also called upon to make decisions on waste disposal procedures, radioisotope handling techniques, and radiation protection matters when there were few if any formalized standards or guidelines to be followed. His varied experience from his graduate school days onward made him eminently qualified to make the decisions. Through the years he served on several committees and subcommittee which prepared policies, regulations or standards for production, distribution, and use of radioisotopes. Dr. Aebersold was an active member of numerous papers at their annual meetings. He constantly urged broader uses of isotopes in medicine, research and all branches of industry.

In his campaign to promote radioisotopes, Dr. Aebersold wrote over 100 articles, gave over 700 talks, and traveled well over 500, 000 miles. Although most of the articles were geared more for a scientist than for laymen, some of them were written in a popular vein and are easily understood by the average citizen. Dr. Aebersold spoke before hundreds of groups ranging from high school science classes and teachers to international scientific conferences in Europ, Asia, South Africa, and South American as well as the United States. He traveled around the world to discuss radioisotopes with scientists who were using them in research and to find out how the U.S. Atomic Energy Commission could better serve them.

Dr. Aebersold married Florence Katherine Martinson on July 7, 1942. their three children are Paul Martin, Alice Constance, and Mickie Claire. Dr. Aebersold died on May 29, 1967.