Abstract
We report coincidence measurements of the (,p) reaction at a beam energy of =165 MeV. The neutral pions were detected by the LAMPF spectrometer and the protons by an array of plastic-scintillator telescopes. The resulting energy resolution for the determination of the excitation energy of the residual nucleus was about 10 MeV. Measurements were performed on at laboratory angles =70°, 80°, 110°, and 130°. The cross section is predominantly quasifree. Its angular dependence follows the trend of the free single-charge-exchange cross section at back angles and is somewhat suppressed relative to this at more forward angles. Events corresponding to removal of p-shell nucleons were identified by their and p energies. The energy spectra for such events are compared to similar pion energy spectra for the (,p) reactions; the cross-section ratios are consistent with ratios calculated from isospin coupling alone. energy spectra are also compared to predictions of Δ-hole model calculations; the calculations for events in which protons are detected at the conjugate quasifree angle underestimate the (,p) cross sections by 30–55 %. At =110° the (,p) reaction was also studied on Fe, Sn, and Pb. No significant A dependence of the cross section was observed.
- Received 24 September 1990
DOI:https://doi.org/10.1103/PhysRevC.43.1255
©1991 American Physical Society