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Author McVoy, K. W.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PHYSICS ♦ CONFIGURATION ♦ COULOMB EXCITATION ♦ DEFORMATION ♦ ELECTRIC MOMENTS ♦ EXCITATION ♦ INTERACTIONS ♦ MAGNETIC MOMENTS ♦ MASS ♦ MATHEMATICS ♦ NEUTRONS ♦ NUCLEAR MODELS ♦ NUCLEAR THEORY ♦ NUCLEI ♦ OCTUPOLES ♦ OPTICAL MODEL ♦ QUADRUPOLES ♦ QUANTUM MECHANICS ♦ SCATTERING
Abstract Recent applications of the nuclear optical model to the description of neutron scattering by spheroidal nuclei showed that "shape effects" are very important for highly deformed nuclei. It was also found that the "adiabatic approximation," which assumes the nucleus to be rigidly fixed in orientation throughout the scattering, is remarkably accurate for very low-energy (S-wave) neutrons. A detailed investigation was made of this approximation, showing that the major factor determining its validity for the heavy nuclei to which it has been applied is the large size of the "effective rotating mass" of the nucleus in comparison to the neutron mass. The effect of a "pear-shaped" deformation, or octupole moment, of the nuclear optical potential on the S-wave neutron strength function was investigated. (A square-edged potential well was used.) This was done for the very heavy nuclei, 225 < A < 240, where the possibility of octupole deformations was suggested by other data. The effect of a small octupole moment for these particular nuclei was found to be largely masked by the nearly indis tinguishable effect of their large quadrupole moments, and, in view of the uncertainty in their quadrupole moments, neutron scattening at this time cannot be said to provide any positive evidence of octupole moments. Cn the contrary, if the quadrupole moments reported from Coulomb excitation measurements are employed, the measured neutron strength function puts an upper limit on the octupole moments of about one-third the quadrupole moment. More accurate data, both on the neutron strength function (as well as R') and on the quadrupole moments, would permit a more accurate estimate of the octupole moments. (auth)
ISSN 0031899X
Educational Use Research
Learning Resource Type Article
Publisher Date 1960-06-01
Publisher Department Brookhaven National Lab., Upton, N.Y.
Journal Physical Review
Volume Number 118
Organization Brookhaven National Lab., Upton, N.Y.


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