Operation Greenhouse. Scientific Director's Report of Atomic Weapon Tests at Eniwetok, 1951. Annex 1.2, Delayed Gamma-Ray Measurements. Part 1. Gamma-Ray Spectrum Measurements (Abridged)
NATIONAL BUREAU OF STANDARDS WASHINGTON DC RADIATION PHYSICS LAB
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The measurement of bomb efficiencies from the number of gamma-rays requires fundamentally two separate experiments. The average number of gamma- rays emitted from the fission fragments delayed gamma-rays per fission must be determined. This experiment can be carried out in the laboratory, A second experiment, the absolute determination of the number of gamma-rays from the bomb are also attempted. Because gamma-rays are not directly observable but are measured only through their secondary effects, and because the probability of occurrence of the secondary effects depends upon the gamma-ray energy, it is not usually possible to count directly the number of gamma-rays in a heterochromatic spectrum. A spectral distribution must be first obtained from which the actual total number of gamma-rays may be computed. This volume discusses the planning for the experiment and the spectral distribution of collimated gamma-rays determined from the Greenhouse tests on two shots. A discussion of measurement of build-up factor which is needed to estimate the effect of collimation is also given.
- Nuclear Instrumentation