Observation of a large longitudinal analyzing power in a nuclear reaction

We have measured the longitudinal analyzing power A(z) of the pp --> pp pi( 0) reaction at 375 MeV bombarding energy. We find that for certain angle co mbinations of the outgoing particles the observed A(z) is as large as 0.3, demonstrating that sizeable longitudinal analyzing powers in reactions with multi-particle final states are possible. This result has implications for pp parity violation experiments above the pion threshold. The observed A, is dominated by the interference between s and p wave pions in conjunction with nucleon-nucleon P waves in the final state. (C) 2000 Elsevier Science B.V. All rights reserved.