INTEGRAL NEUTRON THERMALIZATION. Quarterly Progress Report for the Period Ending December 31, 1962
Neutron spectrum measurements were made in poisoned zirconium hydride and benzene. The results were compared with theoretical calculations. The zirconium hydride spectra showed pronounced hardening and spectral shiit with temperature. Very good experimental and theoretical agreement was obtained for the benzene spectra. Angular spectra were also calculated and measured for 1% borated polyethylene. Experimental and theoretical spectra obtained for the cadmium curtain experiment showed very good agreement at high energies, the lower energy agreement being somewhat reduced. Asymptotic spectra in graphite were calculated in the diffusion approximation for a free gas and for a crystalline scattering kernel. The latter displayed much distortion in agreement with the trapping effect predicted by de Saussure. The total cross section of water was measured up to 100 ev with an apparent accuracy of surface proces 1/2%. A pressure vessel for measuring steady-state neutron spectra in poisoned water at high temperatures was built and tested. Experiments to determine the magnitude of room return in the shielded neutron cave where spectra are measured were made to explain why measured leakage spectra from one-dimensional water slabs are softer than transport theory predictions using DSN. Results showed the effect of room return to be small and in the wrong direction to explain the discrepancy. The sensitivity of the 16-m detector bank was re-evaluated; the effect of precollimator size upon neutron spectra and counting rate was studied; and collimation and shielding on the 50-m station were improved. Calculations of angular and scalar spectra for water poisoned with 1/ absorber, pure water, and multiplying assemblies were made. Results show that for nonmultiplying finite media DSN or GAPLSN (one-dimensional transport theory codes) can be used to calculate spectra in cioser agreement with experiment than previously. For multiplying media, theory and experiment are nearly in agreement for both angular and scalar flux. Scattering of neutrons by polyethylene was studied. Better agreement was achieved between experimental and theoretical spectra for borated polyethylene. Theoretical predictions of the scattering law S( alpha , materials at ) for water were compared with experimental results. Generally good qualitative agreement was obtained, and decreasing the weight of the rotational degree of freedom improved the agreement. Relations for testing the neutron conservation of experimental spectra were also derived. (D.C.W.)
- Research Organization:
- General Atomic Div., General Dynamics Corp., San Diego, Calif.
- DOE Contract Number:
- AT(04-3)-167
- NSA Number:
- NSA-17-026392
- OSTI ID:
- 4695941
- Report Number(s):
- GA-3853
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANGULAR DISTRIBUTION
BENZENE
BORON
CADMIUM
CROSS SECTIONS
CRYSTALS
DSN-CODE
G-CODES
GASES
GRAPHITE
MATHEMATICS
MEASURED VALUES
NEUTRON DETECTION
NEUTRONS
NUMERICALS
PLATES
POISONING
POLYETHYLENES
PRESSURE VESSELS
PROGRAMMING
SCATTERING
SLOWDOWN
SPECTRA
SPECTRAL SHIFT
TEMPERATURE
TRANSPORT THEORY
WATER
ZIRCONIUM HYDRIDES