Gamow-Teller matrix elements from the /sup 11/B(p,n)/sup 11/C reaction at E/sub p/roughly-equal26 MeV

New data are presented for the /sup 11/B(p,n)/sup 11/C reaction taken at 1 MeV intervals for proton bombarding energies in the E/sub p/ = 16--26 MeV range. In the experiment, final states in /sup 11/C up to E/sub x/approx. =10 MeV were clearly identified and differential cross sections were extracted for the first four levels in /sup 11/C. The E/sub p/ = 26 MeV data are examined in microscopic distorted-wave approximation calculations using the wave functions of Cohen and Kurath to describe the states in /sup 11/B and /sup 11/C and using the G matrix interaction of Bertsch et al. for the effective nucleon-nucleon interaction. Gamow-Teller matrix elements for transitions to excited states in /sup 11/C are extracted on the basis of these calculations, thus extending the information on Gamow-Teller matrix elements in the mass 11 systems beyond the ground state matrix element known from ..beta.. decay. Throughout, the results are contrasted with existing information from electromagnetic studies of /sup 11/B. It is concluded that the Cohen-Kurath model places too much Gamow-Teller strength in the low lying states of the mass 11 systems and not enough strength at higher excitation energies. In addition, this model underestimates the net contribution tomore » M1 matrix elements from the isoscalar spin and current and isovector current parts of the M1 operator.« less