Ever since the first nuclear detonation near Alamogordo, N. M., on July 16, 1945, there has been much speculation, and a few full‐scale experiments, on the use of such detonations as a source of neutrons for measurements using time‐of‐flight definition of neutron energy. Although these time‐of‐flight experiments are in principle quite simple, they had to await the solution of a myriad of unusual engineering problems. When the United States and other nations agreed in 1963 to discontinue atmospheric testing of nuclear weapons, the Atomic Energy Commission invested considerable effort in the development of techniques for underground testing. In the course of this work, vacuum flight paths hundreds of meters long were used from time to time. They were quite straight, with antiscattering baffles and provision for closure to contain bomb debris and radioactive gases. The dirt fill around the pipe provided excellent shielding for the neutron collimator, and it was natural at this stage of development to consider the possibility of cross‐section measurements.
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August 1965
August 01 1965
Cross‐section measurements made with neutrons from a nuclear detonation
Time‐of‐flight experiments, conventionally dependent on neutrons from an accelerator, have long been used in the slow grinding out of cross‐section data. Last December, at the AEC's Test Station in Nevada, the vastly larger supply of neutrons from an underground nuclear explosion was employed in a scaled‐up time‐of‐flight experiment. The results of that experiment, which are regarded as preliminary, were reported to the American Physical Society in April, during the 1965 spring meeting in Washington, D.C., and the following article is based on the invited paper presented by Dr. Hemmendinger at that time. More precise results are expected from an experiment carried out on June 11, 1965, data from which are still being processed. The author is a group leader at the Los Alamos Scientific Laboratory in New Mexico.
Physics Today 18 (8), 17–23 (1965);