We describe an experiment in which a 14 GeV/c π- beam was incidenton a hydrogen bubble chamber. Fast forward scattered pions traverseda wire spark chamber spectrometer downstream of the bubble chamber.Events identified as inelastic by the spectrometer induced a trigger ofthe bubble chamber camera. The film produced contained a heavy enrichmentof events of proton diffractive dissociation.
We have studied a sample from this exposure of 4400 events ofthe reaction π-p → π-N* → π-π-π+p. In the two body mass spectra theonly noteworthy feature is the Δ++(1230). In the N* mass spectrum weobserve enhancements at 1.49 GeV, 1.72 GeV, and 2.0 GeV. For the prominent1.72 GeV feature we give estimates of the width and cross sectionas well as evidence favoring a substantial branching fraction toπΔ(1230). We looked for production of N*(1470) followed by decay toπΔ(1230) with negative result. An examination of the Δ++(1230) decaydistribution suggests that the Deck mechanism is the major contributorto the πΔ subchannel.
We tested the s-channel and t-channel helicity conservationrules. We observed violent conflict with sCHC and mild conflict withtCHC. We also tested for simultaneous validity of tCHC and the Gribov-Morrison rule and found no significant contradiction with this dualhypothesis.
