Cross sections for the ]2 C (K-,n-'p) "B reaction have been measured and compared with the results of distorted-wave impulse-approximation calculations that employ the factorization approximation for quasifree scattering. Near the giant dipole resonance of l2 C the calculations underestimate the cross sections for (/r~,/r~'p). The angular distributions for (/r + ,/r + /?) and (/r~\7t~'p) are different and indicate that in this region there is interference between direct decay and semidirect decay.PACS numbers: 25.80.Fm, 24.30.Cz, 27.20.+n The response of the continuum of nuclear states above nucleon breakup threshold to inelastic scattering has been the subject of intensive research.' Transitions to the giant resonances (GR's) can proceed in competition with the quasielastic scattering process. Thus, a detailed understanding of the reaction mechanism is needed in order to unravel the structure of the continuum. For example, the extent to which isospin is a good quantum number for the giant resonances is of great importance in the study of nuclear structure. 2 We believe that coincidence measurements between inelastically scattered probes and emitted secondary particles provide a powerful tool for these investigations. The isospin selectivity of K^ and n~ scattering makes pion probes particularly useful in a study of the continuum.Coincidence experiments involving pions as a probe can be divided into two groups: experiments in the region where quasielastic scattering dominates LE A (target) >: 40 MeV and backward angles] 3 " 7 and experiments in the region of the giant resonances [/^(target) < 40 MeV and forward angles]. 8,9 Indeed, Chant, Rees, and Roos 10 have shown that quasifree single-nucleon knockout calculations, carried out with the code THREEDEE 11 are in good agreement with the measured 12 C(/r + ,K + '/?) !1 B(g.s.) cross sections of Ziock et al. 4 at large momentum transfer and high 2s A -( 12 C). These calculations use a factorized form of the distorted-wave impulse approximation (DWIA), and include optical-model distortions of the incoming pion, outgoing pion, and final-state proton. The processes that contribute to the lower £\-(target) of the continuum, however, are more complicated. It has been suggested 9,12 that, in this GR region, direct decay (due to quasifree-knockout scattering) and semidirect decay (due to resonant inelastic scattering to states of good isospin) compete with each other in a coherent way.The current study is aimed at the excitation region near the giant dipole resonance (GDR) of l2 C. In this Letter, we compare cross sections for the n C(n ± ,n ±, p) reaction with DWIA calculations performed with the code THREEDEE in order to evaluate the importance of quasifree-knockout scattering in the excitation-energy region near the GDR. We also present values for the ratio R^oin*,K*'P)/O (K~,K~'p), which may provide information on the isospin structure of the continuum.The experiment was performed on the Energetic Pion Channel and Spectrometer (EPICS) 13 at Los Alamos National L...