GAMMA-RAY SPECTRA IN FUSION BLANKET MOCK-UPS.
Technical rept. (Doctoral thesis),
MASSACHUSETTS INST OF TECH CAMBRIDGE RESEARCH LAB OF ELECTRONICS
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Gamma-ray spectra were measured in cylinders, 18 inches in diameter and 15-16 inches thick, to evaluate previous theoretical calculations of gamma-ray spectra in proposed fusion reactor blankets see AD-619 669. The cylinders were constructed of 0.5 inch graphite slabs and 1-inch thick layers of lithium-beryllium fluoride salt mixture contained in aluminum pans. Molybdenum plates were used to approximate first walls, 0-1.25 inches thick. The cylinders were irradiated by 14-Mev neutrons produced by bombarding a tritium target with a beam of deuterons from a 150-kilovolt CrockroftWalton accelerator. The target was positioned on the center line of the cylinder, 5.25 inches from its base. The gamma-ray spectra were measured by collimating a beam of gamma rays leaking out of the side of the blanket mock-up and by using a sodium iodide scintillation crystal as a detector. The gamma-ray spectra from the graphite assemblies are characterized by a large peak at 4.43 Mev, a smaller peak at 6.87 Mev, and a still smaller peak at 4.95 Mev. The spectra in the salt assemblies are characterized by large peaks at 6.63 Mev and 5.13 Mev, and several smaller peaks. The relative magnitudes of these peaks at different depths in the assemblies are in agreement with previous theoretical calculations. Author