SCATTERING OF 15.2 Mev NEUTRONS BY COMPLEX NUCLEI

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1961

OSTI ID:4008084

Walker, W S

A need for additional data on neutrons elastically scattered by deformed heavy nuclei prompted a measurement of the elastic angular distributions of 15.2 Mev d-t neutrons on tantalum, thorium, and uranium. The associated particle technique was used with a time-topulse-height converter to measure the time of flight of neutrons over a distance of 179 cm. The percent energy resolution at 15.2 Mev was 16%. The neutron detector was a 13 cm diameter by 15 cm long plastic scintillator. Cylindrical scatterers were used, and the angular distributions were taken from 10 to 162 deg in 2 to 10 deg intervals. For comparison with a spherical nucleus, the angular distribution for Bismuth was also measured. The data were corrected for muitiple scattering through the first minima of the angular distributions by an analytical method. Data were obtained for several thicknesses of Ta and Bi in order to check the multiple scattering correction. The results were compared with the spin-orbit spherical optical potential calcu1ations computed by Bjorklund and Fernbach for the four elements at 15.2 Mev. The experimental Ta cross section is slightly smoothed out compared to the theoretical cross section, but the large discrepancies known to exist at 7 Mev for Ta were not found. The conclusion is that the deformation effect is not as large at 15.2 Mev. The Th and U cross sections are nearly identical, as expected from the nearness of their atomic weights. The measurements for Th and U do not show the very deep first minima predicted by the spherical potential. This discrepancy may be the effect of contributions to the measured cross section from the low-lying states. Also, Th and U are outside of the range of atomic weights used to set the optical model parameters, and the discrepancies may reflect this rather than a deformation effect. The experimertal and theoretical cross sections for Bi are in good agreemert. (Dissertation abstr., 24: No. 9, March 1964)

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-18-021340
• OSTI ID: 4008084
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ANGULAR DISTRIBUTION
BISMUTH
CONFIGURATION
CROSS SECTIONS
ELASTIC SCATTERING
ENERGY RANGE
INTERACTIONS
MEASURED VALUES
MEV RANGE
NEUTRON BEAMS
NEUTRON DETECTION
NEUTRON SPECTROMETERS
NUCLEAR MODELS
NUMERICALS
OPTICAL MODEL
ORBITS
PHOSPHORS
PHYSICS
PULSES
SCATTERING
SPIN
TANTALUM
THORIUM
TIME OF FLIGHT METHOD
TRANSDUCERS
URANIUM