OPERATION SANDSTONE. Nuclear Explosions. 1948. Scientific Director's Report of Atomic Weapon Tests. Annex 4, Part 11. Neutron Absorption Measurements during OPERATION SANDSTONE.
Sandstone rept. no. 19,
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The flux of fast neutrons of energy greater than 3 Mev was measured by means of sulphur, and neutrons of this energy were found to be lethal assuming 10 to the 11th power is lethal at distances from 650 yards in Test Yoke to 500 yards in Test Zebra. The slow neutron flux as measured with arsenic in Test Zebra indicated that these would have been lethal assuming 5 x 10 to the 11th power neutrons per sq. cm. is lethal at about 100 yards greater distance than at the sulphur neutrons. Absorption measurements made with steel and concrete indicate that 3 inches of concrete and 2 inches of steel are required to reduce the fast neutron flux by a factor of 2. Six inches of steel on all sides were found necessary to reduce the slow neutron flux by a factor of 2, and concrete was found to be less effective in cutting down the number of slow neutrons. In general, the fast neutrons travel in the direction away from the point of detonation, but the slow neutrons were found to be non directional.
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