ATTENUATION OF POINT SOURCE GAMMA RADIATION IN SLABS. Final Report

Technical Report · Sat Sep 01 04:00:00 EDT 1962

OSTI ID:4772824

Mehlhorn, H A; Clarke, E T; Gold, R; McMath, R

Protection afforded by structures against gamma rays due to a nuclear explosion in the atmosphere is investigated, both theoretically and experimentally. Calculations are made for the differential dose-rate spectrum (in air) due to fission products, and the differential dose spectrum to thermal neutron capture in nitrogen, as a function of distance from the explosion and time, extending for several minutes after the explosion. Integration of the spectra over photon energy and time show the accumulated air dose due to nitrogen capture to be far superior to that from fission products for several minutes at most distances. The superiority increases with distance and decreases with time. Some effects of nuclear weapon design on these conclusions are discussed. Data are reported for an experimental program providing measurements of attenuation of gamma rays in steel slabs, to compare with theoretical work being done at the National Bureau of Standards. Gamma rays from a cobalt-60 source, suspended in air, strike a steel slab at three angles of incidence. Transmitted radiation is detected by five ionization dose-rate meters at various distances below the slab. Information is given for 2-ft square slabs from 1/4 to 2 in. thick, and detectors from 1 to 6 ft distant. It was found that slabscattered radiation was approximately proportional to the solid angle subtended by the slab, that less radiation was transmitted at large polar angles of incidence, and that at least 2 in. of steel is needed to produce shielding improvement in a slab-covered hole. (auth)

• Research Organization: Technical Operations, Inc., Burlington, Mass.
• NSA Number: NSA-17-004210
• OSTI ID: 4772824
• Report Number(s): DASA-1318; TO-B-62-13
• Country of Publication: United States
• Language: English

Related Subjects

ABSORPTION
AIR
ANGULAR DISTRIBUTION
CAPTURE
COBALT 60
CONFIGURATION
DOSEMETERS
ENERGY
FISSION PRODUCTS
GAMMA DETECTION
GAMMA RADIATION
GAMMA SOURCES
HOLES
IONIZATION
IONIZATION CHAMBERS
MEASURED VALUES
NITROGEN
NUCLEAR EXPLOSIONS
NUCLEAR REACTIONS
NUMERICALS
PHOTONS
PHYSICS
PLANNING
PLATES
RADIATION DOSES
SCATTERING
SHIELDING
STEELS
THERMAL NEUTRONS
THICKNESS