Measurement of spin observables in the Si28(p→,p→ ’) reaction at 500 MeV and comparison with the distorted-wave impulse approximation

Analyzing power A(y) and spin-transfer observables D(ij) have been measured for 500-MeV proton inelastic scattering from Si-28. Measured values of the D(ij) for the 9.70-MeV 5-, T = 0, the 11.58-MeV 6-, T = 0, and the 14.35-MeV 6-, T = 1 states are reported at 17-degrees and 22-degrees; values of A(y) cover the range from about 10-degrees to 26-degrees. Nonrelativistic (NRIA) and relativistic (RIA) impulse-approximation calculations are compared with the data. The differences between the two types of calculations are generally small. The RIA yields excellent agreement with the D(ij) data for the 5- state, and both RIA and NRIA do well for D(ij) data for the 6-, T = 0 state but poorly for the 6-, T = 1 state. For the A(y) data, both types of calculation give fairly good predictions for the 5- and 6-, T = 1 states, but not for the 6-, T = 0 state. Comparison between theory and experiment for the combinations of observables D(k), which are sensitive to individual terms in the nucleon-nucleon interaction, indicates a possible need for medium corrections in the T = 1 tensor and spin-orbit forces.