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Energy dependence of neutron-proton matrix element ratios derived from 25--800 MeV energy proton scattering

Journal Article · · Phys. Rev. C; (United States)
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New data are presented on elastic and inelastic proton scattering by /sup 58/Ni at 333 and 498 MeV and /sup 208/Pb at 318 MeV. We have analyzed these data using phenomenological distorting potentials and potentials generated by folding neutron and proton densities with a free nucleon-nucleon t matrix or with a medium modified nucleon-nucleon interaction. Making use of electromagnetic matrix elements, or charge transition densities, we have calculated neutron-proton transition matrix element ratios in the vibrating potential--vibrating density model (''collective form factors''), or with a scaling model in which the neutron transition densities are taken as proportional to the proton densities. In addition, we have calculated, neutron-proton matrix element ratios from earlier (p,p') results at 25--800 MeV for /sup 40/Ca, /sup 58/Ni, and /sup 208/Pb. We conclude that, although there are some irregularities, the derived neutron/proton matrix element ratios for natural parity states show a tendency to decrease in magnitude with decreasing proton energy in the range 500--100 MeV. A quantitatively similar effect is seen in the ratio of experimental to theoretical cross sections, where the latter are calculated using transition densities adjusted to fit electron or 800 MeV proton scattering. We attribute these results to a failure of the impulse approximation and the vibrating potential model in this energy region.

Research Organization:
School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455
OSTI ID:
5670534
Journal Information:
Phys. Rev. C; (United States), Journal Name: Phys. Rev. C; (United States) Vol. 37:2; ISSN PRVCA
Country of Publication:
United States
Language:
English

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Related Subjects

651520* -- Nuclear Properties & Reactions
A=39-58
Experimental
651920 -- Nuclear Properties & Reactions
A=190-219
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCELERATORS
ANGULAR MOMENTUM
BARYON REACTIONS
BARYON-BARYON INTERACTIONS
BORN APPROXIMATION
CALCIUM 40 TARGET
CHARGED-PARTICLE REACTIONS
DWBA
ELASTIC SCATTERING
ENERGY LEVELS
ENERGY RANGE
EVEN-EVEN NUCLEI
HADRON REACTIONS
HADRON-HADRON INTERACTIONS
HEAVY NUCLEI
IMPULSE APPROXIMATION
INELASTIC SCATTERING
INTERACTIONS
INTERMEDIATE MASS NUCLEI
ISOTOPES
LAMPF LINAC
LEAD 208
LEAD 208 TARGET
LEAD ISOTOPES
LINEAR ACCELERATORS
MATRIX ELEMENTS
MESON FACTORIES
MEV RANGE
MEV RANGE 100-1000
NICKEL 58
NICKEL 58 TARGET
NICKEL ISOTOPES
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEON-NUCLEON INTERACTIONS
OPTICAL MODELS
PARITY
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
PROTON REACTIONS
SCATTERING
SPIN
STABLE ISOTOPES
TARGETS