PION-PRODUCTION IN PD INTERACTIONS

Recent experimental data for the reaction pd --> pd pi degrees in the pion momentum range eta = p(c.m.max)(pi degrees)/m(pi degrees)c less t han or equal to 0.96 is discussed. The excitation function sigma(pd pi degrees) (T-p) roughly follows a eta(4) power law for Ss wave interac tion; close to threshold it is compatible with that for pd --> He-3 pi degrees, i.e. a strong spin-dublett interaction. The model of a quasi -fi ee elementary process np --> d pi degrees with a spectator proton describes sigma(pd pi degrees) (T-p), too, but does not exhaust the ob served spectator energy spectra. Comparison to isospin related pd --> nd pi(+) data indicates another reaction mechanism contributing with a strength comparable to that of the quasi-free process.