Abstract
Pion absorption by was studied at =165 MeV in a kinematically complete experiment. The cross section for absorption on a (pn) pair of nucleons, (), was found to be 17.0±2.6 mb; that for absorption on a (pp) pair, (), 0.91±0.20 mb. The angular distribution in the πNN center-of-mass system for () resembles that for the +d→p+p reaction while the angular distribution for () is strongly backward peaked. Evidence that a significant fraction of the absorptions involves all three target nucleons is seen in the angular correlation between the two detected nucleons as well as in the momentum distribution of the unobserved nucleon. For and absorption, the three-body cross sections were found to be 9.6±2.1 and 4.2±01.2 mb, respectively. Neither initial- nor final-state interactions appear to be major contributors to the observed three-body absorption, though initial-state interactions may be contributing to the enhancement of the three-body absorption at the Δ resonance.
- Received 29 October 1990
DOI:https://doi.org/10.1103/PhysRevC.43.957
©1991 American Physical Society