Electromagnetic structure of the helium isotopes

Journal Article · Fri Apr 01 00:00:00 EST 1977 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.15.1396· OSTI ID:7223955

McCarthy, J S; Sick, I; Whitney, R R

The elastic-electron scattering cross sections from /sup 3/He and /sup 4/He have been measured at incident electron energies between 170 and 750 MeV. Cross sections were separated into their longitudinal (charge) and transverse (magnetic) contributions using the Rosenbluth formula. Values of the /sup 3/He charge form factor have been extracted to q/sup 2/ = 20 fm/sup -2/ and for the /sup 3/He magnetic form factor to q/sup 2/ = 16 fm/sup -2/. The /sup 4/He form factor has been determined up to 6.2 fm/sup -2/. Densities for the charge and magnetization have been deduced from phenomenological models used in a phase-shift solution of the Dirac equation. A model-independent determination of the nuclear densities has been performed in order to obtain realistic errors on the extracted distributions. After unfolding the nucleon size from the distributions the point density is shown to have a significant central depression for a radius <0.8 fm for both /sup 3/He and /sup 4/He. Comparison of the form factors is made with Faddeev and variational three-body calculations that use realistic two-body NN interactions. The influence of off-shell effects, three-body forces, meson-exchange corrections, and short-range correlations are discussed. At present no theoretical calculation that uses input derived entirely from nucleon-nucleon scattering is able to reproduce the experimental data.

• Research Organization: Department of Physics, University of Virginia, Charlottesville, Virginia 22901
• OSTI ID: 7223955
• Journal Information: Phys. Rev., C; (United States), Vol. 15:4
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ELECTRON REACTIONS
ELASTIC SCATTERING
HELIUM 3
ELECTROMAGNETIC FORM FACTORS
HELIUM 3 TARGET
HELIUM 4
HELIUM 4 TARGET
CROSS SECTIONS
EXCHANGE INTERACTIONS
FADDEEV EQUATIONS
MEV RANGE 100-1000
SHELL MODELS
THREE-BODY PROBLEM
CHARGED-PARTICLE REACTIONS
ENERGY RANGE
EQUATIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FORM FACTORS
HELIUM ISOTOPES
INTERACTIONS
ISOTOPES
LEPTON REACTIONS
LIGHT NUCLEI
MANY-BODY PROBLEM
MATHEMATICAL MODELS
MEV RANGE
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
PARTICLE PROPERTIES
SCATTERING
STABLE ISOTOPES
TARGETS
651225* - Nuclear Properties &amp; Reactions
A=1-5
Experimental- Nuclear Reactions &amp; Scattering- (-1987)