Springer Online Journal Archives 1860-2000
Abstract Elasticα-scattering angular distributions have been measured atE α=36.2 MeV, 39.6 MeV, 42.6 MeV, 49.5 MeV, 61.0 MeV for40Ca and atE α=36.2 MeV, 42.6 MeV, 49.5 MeV and 61.0 MeV for44Ca, respectively. At backward angles the data display an oscillatory structure forE α〈50 MeV and more smoothly decreasing slopes atE α =61.0 MeV resembling the data obtained at higher energies. The40Ca data belowE α =50 MeV show the well known backward enhancement, which at 42.6 MeV and 49.5 MeV can be fitted by aP 14 2 and aP 16 2 respectively. Together with previous data,P L 2-structures have now been observed for allL-values betweenL=8 andL=16. The slope of the curveL(L+1) versus excitation energy is slightly smaller forL〉12 than forL〈12. Optical model analyses (within a Woods-Saxon-folding model) lead to large differences between the44Ca and40Ca parameters. Furthermore, in our parametrization, the40Ca real potential depth shows dramatic changes with energy. This feature seems outside the domain of the optical model and requires consideration of additional effects (e.g. antisymmetrization) not included in the standard optical model. Present microscopic calculations on the basis of the Resonating Group Method are discussed in connection with the characteristic features ofα-scattering from40Ca.
Type of Medium: