PI(-]PI(+)PI(+())-) ON DEUTERIUM AT T-PI+ = 283 MEV/

New experimental results on the pi(+) d --> pi(+)pi(-) pp and pi(+) d --> pi(+) pi(+) nn reactions at Tpi+ = 283 MeV are presented. In-plane coincidence data were taken with the CHAOS spectrometer using pions f rom the M11 channel at TRIUMF. Because of the quasi-free nature of the pion-production reaction, the present study is equivalent to studying the elementary pi(+) N --> pi(+) pi(+/-) N reactions on protons and n eutrons simultaneously. These exclusive measurements provide a set of many-fold differential cross sections which are an ideal testing groun d for microscopic models describing the pi N --> pi pi N reaction. The interpretation of the data relies on a model which is based on effect ive chiral Lagrangians to describe the piece of the reaction that incl udes only pi's and N's, and on effective Lagrangians to account for in termediate Delta's and N*'s. The measured many-fold differential cross sections are used to constrain some parameters of the model (xi, f De lta, C, g(N*Delta pi) and g(N*N pi)). Finally, the pi(+) pi(+/-) invar iant mass distributions display no evidence of strongly interacting pi on pairs in either the I = J = 0 or the I = 2 J = 0 channels. (C) 1998 Elsevier Science B.V.