Quasifree scattering of positive pions on carbon

We have studied the reaction ¹²C(π⁺,π⁺p)¹¹B in a coincidence experiment that completely determined the kinematics of each event. The energy resolution was sufficient to identify the truly quasifree events, i.e., those that left the residual nucleus in its ground state. A comparison of our data with empirically normalized plane wave impulse approximation calculations shows reasonable agreement as long as only one parameter is varied at a time. Some effects of the nuclear shell structure can be seen. There is an indication that the (3 / 2,3 / 2) resonance may be narrowed inside a nucleus.

NUCLEAR REACTIONS ¹²C(π⁺,π⁺p), E=130-200 MeV; measured σ(E,θ,E^′), PWIA analysis. Resolution ∼ 1 MeV, θ_π=-60°-130°, θ_p=30°-45°.