Angular distributions and excitation functions for inelastic scattering of and from were measured at incident pion energies near the resonance. Three states at excitation energies 11.7, 15.2, and 17.3 MeV were identified as states. Isovector and isoscalar spectroscopic amplitudes and , and equivalently, neutron and proton amplitudes and were deduced by comparison with microscopic distorted wave impulse approximation calculations. The 11.7-MeV state was found to be excited with a amplitude ratio of -1/3, resulting in a complete cancellation of the cross section. A nearly pure proton excitation was observed for the transition to the 17.3-MeV state. Both results are in qualitative agreement with the presented shell-model calculations. A poor correspondence with theory is found for the 15.2-MeV state. Data and distorted-wave impulse approximation calculations using shell-model wave functions are presented for the first state at 6.73 MeV as an example of a transition dominated by ΔS=0 (no spin transfer). Its excitation function and angular-distribution shape contrast sharply with the transitions to the states that proceed by ΔS=1.
- Received 3 July 1984
- Published in the issue dated March 1985
© 1985 The American Physical Society