Coincidence measurements of the (. pi. /sup +/,. pi. /sup 0/p) reaction in the /triangle/-resonance region

Abstract

This thesis describes an experimental study of the (..pi../sup +/, ..pi../sup 0/p) reaction at incident energy T/sub ..pi../sup +// = 165 MeV. This work is part of the first experiment to detect neutral pions and protons in coincidence in kinematically complete measurements. The reaction was studied on /sup 16/O (using water targets) at several pion angles: theta/sub ..pi../sup 0// = 70/degree/, 80/degree/, 110/degree/, and 130/degree/. At theta/sub ..pi../sup 0// = 110/degree/ measurements were also made on /sup 56/Fe, /sup 120/Sn, and /sup 208/Pb. The neutral pions were detected with the LAMPF ..pi../sup 0/ spectrometer, while the protons were detected in a vertical array of plastic-scintillator ..delta..E-E telescopes, each spanning 8.5 msr. Energy spectra of the differential cross sections d/sup 4/sigma/dE/sub ..pi../sup 0// dE/sub p/d..cap omega../sub ..pi../sup 0//d..cap omega../sub p/ were obtained for each proton telescope and subsequently integrated over proton and pion energy and proton angle. The characteristics of these spectra are consistent with a quasi-free description of the (..pi../sup +/,..pi../sup 0/p) reaction. The angular dependence of dsigma/d..cap omega../sub ..pi../sup 0//(theta/sub ..pi../sup 0//) for /sup 16/O(..pi../sup +/,..pi../sup 0/p) was found to be in accordance with that of the cross section for the corresponding free reaction at backward ..pi../sup 0/ angles.more » For the /sup 16/O(..pi../sup +/,..pi../sup 0/p) reaction, events in which a p-shell nucleon had been removed were identified. The p-shell events were found to constitute only 40--50% of the total cross section for quasi-free one-nucleon removal. The (..pi../sup +/,..pi../sup 0/p) cross section at theta/sub ..pi../sup 0// = 110/degree/ proved to be almost the same for all target nuclei, possibly slightly decreasing as a function of A. 102 refs., 108 figs., 24 tabs.« less