Pion-Induced Production on Deuterium.

The reactions pi^+d to pi^-pi ^+pp and pi^-d to pi^+pi ^-nn were studied at incident pion kinetic energies of 250 MeV, 331 MeV, and 450 MeV. This energy range spans the Delta resonance region, in which meson currents should be the most pronounced. For each reaction the doubly differential cross section {d^2sigmaover dOmega dT} was measured for the reaction by observing the pions of opposite sign of charge from the incident beam with a single arm magnetic spectrometer. The integrated cross sections were calculated for each reaction from this data. A quasi-free calculation of pion-induced pion production was done, and the results of this calculation show that the quasi-free process accounts for over eighty percent of the integrated cross section. The results are in sharp contrast to a meson current model. The reaction pi^-p to pi^+pi^-n was studied at 450 MeV to and the doubly differential cross section {d^2sigmaover dOmega dT} were measured to complete a previous set of measurements at lower energy; this allowed a comparison of pion-induced pion production on deuterium to pion-induced pion production on the proton over the entire energy range of the experiment. This experiment was performed at the Los Alamos Meson Physics Facility (LAMPF) at the Los Alamos National Laboratory (LANL) in Los Alamos New Mexico.