Neutron emission following radiative pion capture in complex nuclei

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Virginia Polytechnic Institute and State University

This thesis contains an account of a measurement of the neutron energy spectrum from radiative pion capture in carbon, oxygen and calcium. The measurement was performed at six n-γ correlation angles for the case of carbon and oxygen, and seven n-γ correlation angles for the case of calcium. The observed energy spectra fall off approximately exponentially between 2 and 30 MeV. Evidence of resonance structure was observed at about 4 MeV in the energy spectra of carbon and oxygen. This is in agreement with a theoretical prediction of the giant multipole excitation model. The neutron yield versus n-γ correlation angles peaks at 180° for all three nuclei studied. This indicates the quasi-free mechanism also plays an important role in the radiative pion capture process.