Analyses of fast neutron inelastic scattering cross sections to higher (vibrational) states of /sup 232/Th and /sup 238/U. I. Standard formalism

Journal Article · Wed Sep 01 04:00:00 EDT 1982 · Phys. Rev. C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.26.841· OSTI ID:7059851

Chan, D W.S.; Egan, J J; Mittler, A; Sheldon, E

Angle-integrated cross-section data in the form of excitation functions from threshold to 2.5 MeV incident (lab) energy, as measured and calculated, are presented for inelastic scattering of fast neutrons on /sup 232/Th and /sup 238/U, proceeding to higher collective (quadrupole and octupole vibrational) states of these deformed actinide nuclei. The experimental (n,n') data were for the most part obtained from corrected ..gamma..-production (n,n'..gamma..) yields. The theoretical data were derived from an incoherent sum of the compound-nuclear and strong-coupling direct-interaction cross sections, computed using the Bruyeres set of optical potential and deformation parameters. The relative coupling strength was the sole adjustable parameter. Provision was made for the effect of Moldauer level-width fluctuations and for competing neutron exit channels (but not for radiative capture, charged-particle, of fission competition); the coupled-channels computations permitted up to six levels to be coupled simultaneously. The ensuing ''standard'' theoretical level excitation functions matched the experimental data fairly closely in most instances, confirming the viability of this conventional method of analysis. However, indications of potentially still better fits were provided by preliminary calculations employing the unified statistical S-matrix formalism of Weidenmueller et al. As illustrated for (n,n') scattering to the lowest members of the K = 0/sup -/ octupole band in /sup 232/Th and /sup 238/U, the latter approach reproduces experimental trends closely when the relative coupling strength is optimized. A subsequent paper will present detailed results of the unified analyses and comparisons with evaluated neutron data-file excitation functions for these actinide target nuclei.

• Research Organization: Department of Physics and Applied Physics, University of Lowell, Lowell, Massachusetts 01854
• OSTI ID: 7059851
• Journal Information: Phys. Rev. C; (United States), Journal Name: Phys. Rev. C; (United States) Vol. 26:3; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

652023* -- Nuclear Properties & Reactions
A=220 & above
Experimental-- Energy Levels & Transitions-- (-1987)
652025 -- Nuclear Properties & Reactions
A=220 & above
Experimental-- Nuclear Reactions & Scattering-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
ANGULAR DISTRIBUTION
BARYON REACTIONS
COUPLED CHANNEL THEORY
CROSS SECTIONS
DEFORMED NUCLEI
DISTRIBUTION
ENERGY LEVELS
EVEN-EVEN NUCLEI
EXCITATION FUNCTIONS
EXCITED STATES
FUNCTIONS
HADRON REACTIONS
HEAVY NUCLEI
INELASTIC SCATTERING
ISOTOPES
NEUTRON REACTIONS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
RADIOISOTOPES
SCATTERING
TARGETS
THORIUM 232
THORIUM 232 TARGET
THORIUM ISOTOPES
TOTAL CROSS SECTIONS
URANIUM 238
URANIUM 238 TARGET
URANIUM ISOTOPES
VIBRATIONAL STATES
YEARS LIVING RADIOISOTOPES