STUDY OF neutrino D CHARGED CURRENT TWO PION PRODUCTION IN THE THRESHOLD REGION

We present our final results on double-pion production by muon-type neutrinos observed in a 2.4 x 10/sup 6/ (365 000) picture exposure of the Argonne 12-foot deuterium- (hydrogen-) filled bubble chamber. The reactions ..nu..d..--> mu../sup -/..pi../sup -/..pi../sup +/pp/sub s/, ..nu..d..--> mu../sup -/..pi../sup +/..pi../sup 0/pn/sub s/, and ..nu..d..--> mu../sup -/..pi../sup +/..pi../sup +/nn/sub s/ are studied. The data, which shows strong ..delta..(1236) production, has nucleon-..pi..-..pi.. mass distribution peaked at low masses in all three reactions. The excitation functions for the three reactions exhibit a rapid rise over the energy range from threshold up to about 3 GeV, but thereafter the energy dependence appears less pronounced. The threshold behavior of the cross sections for these reactions is analyzed in the context of a model developed by Adjei, Dicus, and Teplitz. Data from the constrained reaction, ..nu..d..--> mu../sup -/..pi../sup -/..pi../sup +/pp/sub s/, satisfy the Adler conserved-vector-current test.