Elastic scattering of alpha particles near the Coulomb barrier and matter distribution of medium and heavy nuclei

Journal Article · Wed Mar 01 04:00:00 EST 1978 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.17.978· OSTI ID:6928200

Badawy, I; Berthier, B; Charles, P; Dost, M; Fernandez, B; Gastebois, J; Lee, S M

The elastic scattering of ..cap alpha.. particles near 180/sup 0/ was measured in the vicinity of the Coulomb barrier for /sup 110,112,114,116/Cd, /sup 112,114,116,118,120,122,124/Sn, /sup 122,124,126,128,130/Te, /sup 144,148,150,152/Sm, and /sup 204,206,208/Pb. An optical model analysis using Woods-Saxon potentials shows that the usual parameters of the real part of the potential V, R/sub opt/ and a must obey the relationship Vexp((R/sub opt/ - R/sub 0.2/)/a) 0.2 MeV in order to fit the data. The ..cap alpha..-nucleus distance R/sub 0.2/ at which the nuclear potential depth is -0.2 MeV can then be determined for each nucleus within +- 0.03 fm. An analysis in terms of a folding model was performed for /sup 2/08Pb and /sup 1/24Te. For the class of potentials thus obtained, it is the ga-nucleus distance at 0.5 MeV depth rather than at 0.2 MeV that appears to be best determined. The same analysis determines the radius R/sub FD0.002 at which the nucleon density is 2 x 10/sup -/3 nucleon/fm/sup 3/. The value of R/sub FD/ is found to depend mostly on the ..cap alpha..-nucleon effective interaction used, and very little on the functional form of the density distribution. Further evidence is presented in favor of the Gaussian interaction -U/sub 0/ exp(-K/sup 2/r/sup 2/) with U/sub 0/ = 127 MeV and K = 0.6 fm/sup -/1, which has been proposed by Sumner and which leads to the probable value R/sub FD/ = R/sub 0.2/ - (3.06 +- 0.03) fm. Other interactions are not excluded, however, and considering those proposed so far in the literature leads to R/sub FD/ = R/sub 0.2/ -(3.11 +- 0.14) fm. The average variation of R/sub FD/ with mass number is found to be = (1.355A/sup 1/3/ + 0.87) fm for spherical nuclei. The rate of variation of with mass number is found to be in good agreement with the droplet model predictions, which is taken as an evidence that the surface thickness of spherical nuclei is practically constant from Sn to Pb.

• Research Organization: Departement de Physique Nucleaire CEN Saclay,BP 2, 91190 Gif-sur-Yvette, France
• OSTI ID: 6928200
• Journal Information: Phys. Rev., C; (United States), Journal Name: Phys. Rev., C; (United States) Vol. 17:3; ISSN PRVCA
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA REACTIONS
ANGULAR DISTRIBUTION
CADMIUM ISOTOPES
CHARGED-PARTICLE REACTIONS
COULOMB FIELD
DISTRIBUTION
ELASTIC SCATTERING
ELECTRIC FIELDS
ISOTOPES
LEAD ISOTOPES
MATTER
NUCLEAR MATTER
NUCLEAR POTENTIAL
NUCLEAR REACTIONS
OPTICAL MODELS
RARE EARTH ISOTOPES
SAMARIUM ISOTOPES
SCATTERING
TELLURIUM ISOTOPES
TIN ISOTOPES
WOODS-SAXON POTENTIAL