Folding model analysis of inelastic alfa particle scattering to giant resonances

Abstract

The hybrid single-folding model is used to calculate cross sections for the inelastic scattering of 240 MeV alpha particles by 5 8Ni and " 116Sn. Potential parameters were obtained from recent elastic scattering data covering an angular range of 2-320.Data for the Ex= 1 .454 MeV 1=2 and Ex=4.475 MeV 1=3 states in 58 Ni were fit well with deformation parameters obtained from electromagnetic B(EI) values. The experimental Ex=16.08 MeV peak was fit by 1=2 calculations corresponding to 45+5% (42+5% -3% -2%) of the E2 energy-weighted sum rule (EWSR) for the folding (deformed potential) model, which were in good agreement with previous work. The experimental Ex=17.42 MeV peak was fit by a combination of 1=0 and 1=2 calculations corresponding to 19:t2% (4O-t2%) of the EO EWSR and 73︢% (8+5%-3% ) of the E2 EWSR with the folding (deformed potential) model. The EO EWSR contribution from the folding model is considerably smaller than from previous folding model calculations.116 For n. the data for the Ex=1.29 MeV 1--2 state was fit well using the electromagnetic B(E2) value. However the shape of the angular distribution for the EX=2.27 MeV 1=3 state was not well reproduced at smaller angles. The experimental Ex=13.2 MeV and Ex=15.6 MeV peaks were fit by 1=2 and 1=0 calculations corresponding to 961︢5% of the E2 EWSR and 1061︢4% of the EO EWSR, in excellent agreement with previous deformed potential results. The EX=21.8 MeV peak was fit by an 1=3 calculation corresponding to 90-+5% of the E3 EWSR, substantially higher than deformed potential results. For 58 Ni where only a small art of the GMR has been located, cross sections for p GMR excitation changed significantly when hybrid folding model potential angular range, even though cross sections for low-lying 1=2 and 1=3 states were nearly the same for both cases.