Coupled-channels and fluctuations analysis of deuteron stripping and deuteron scattering on 20Ne

The first three states in 21Ne (ground state 3 2 + , 0.35 MeV 5 2 + and 1.75 MeV 7 2 + ) were studied with the 20Ne( d , p)21Ne reaction. Differential cross section and vector analyzing power angular distributions at 7 energies between 10 and 12 MeV were measured. In addition, excitation functions for the differential cross section were obtained for these three states, between 9 and 13 MeV in steps of 50 keV, at four backward scattering angles of 90, 108.3, 131.7 and 150 degrees. A statistical analysis of the observed fluctuations was performed to separate the compound-nuclear contribution to the cross section from the direct contribution. A quantitative estimate of the compound contribution could be made since the absolute normalization of the Hauser-Feshbach calculation was determined from the fluctuation analysis. The energy-averaged angular distributions were compared to the sum of compound and direct calculations. For the 5 2 + state a one-step direct-reaction calculation was found to be reasonably adequate. Calculations were compared with the data for all three transitions using the coupled-channels approach with spectroscopic amplitudes obtained from a shell-model calculation. In general, the fits to the data were not very good. Elastic and inelastic deuteron scattering to the ground state 0+ and to the excited 2+ state were also measured. These data were compared to optical-model and coupled-channels calculations.