Neutrons from radiative pion capture in carbon, oxygen, and calcium

Abstract
The energy spectra of neutrons between 2 and 28 MeV emitted following radiative pion capture in carbon, oxygen, and calcium fall off exponentially. An enhancement, however, is observed for neutron energies below 5 MeV in carbon and oxygen. Neutron yield peaks at nγ angles of 180°, indicating a quasifree absorption mechanism in this process.