Effective Interactions and Structure in Medium Energy (proton, Proton') Experiments.
Differential inelastic cross sections have been measured for seven transitions in ('90)Zr, with 121.5 MeV protons. Analyzing powers and differential inelastic cross -sections have been measured for three transitions in ('89)Y with 200.5 MeV protons, for two transitions in ('94)Zr with 159.6 MeV protons, and for the transition to the doublet at 2.64 MeV in ('207)Pb with 199.7 MeV and 495 MeV protons. From 'consistent' distorted waves (CDW) calculations (using the same force in the transition potential and optical potentials) neutron transition densities were extracted by fits to the most prominent maximum of the measured cross sections; smaller values were extracted when the new Juelich density-dependent (D-D) force GBJ was used in place of the Hamburg D-D force GPH. 'Consistent' calculations with a free force L-F, with the same neutron strengths as with the D-D force GPH, predicted cross sections with too much diffraction structure. Calculations with phenomenological distorted waves (PHDW) yielded smaller neutron strengths (than with CDW) and gave poorer shapes of cross sections for lower multipole transitions (J = 2 or 3), but better descriptions for the higher multipoles (J = 4, 5, 6). With the quenching suggested by electromagnetic rates, the tensor force appears too strong because the spin-flip contribution spoiled the agreement with the cross section shape of the data for the 9/2('+) state in ('89)Y. Using core proton contributions estimated from an earlier ('90)Zr experiment, microscopic calculations as 159.6 MeV provided very good shapes of analyzing powers and cross sections for transitions to neutron states in ('94)Zr. 'Consistent' calculations at 199.7 MeV with the D-D force GPH and at 199.7 and 495 MeV with the free force L-F, and the new Juelich RPA transition densities, predicted cross-section magnitudes in exact agreement with the present data for the transition to the doublet at 2.64 MeV in ('207)Pb.
- Pub Date:
- Physics: Nuclear