The TRIUMF Parity Violation Experiment

Experiment (E497) at TRIUMF which measures the parity violating longitudinal analyzing power, A_z, in pp scattering is close to completion. The proton beam energy of 221 MeV is chosen to isolate the ^3P_2-^1D₂ partial wave contribution to A_z. A desired precision of ± 2× 10^-8 statistics and systematics is expected at the completion of the experiment. Systematic errors have been carefully minimized by tuning of the polarized ion source, the TRIUMF cyclotron, and the E497 beamline. The residual helicity correlated beam parameters are extremely small and are monitored by specialized auxiliary instrumentation. These measurements are used to correct the measured asymmetry to extract A_z. All of the corrections are small compared with the statistical precision except the correction for the intrinsic first moments of polarization. Three major data taking runs each with a statistical error of ± 4× 10^-8 have now been completed and analyzed. Another data taking run has recently been completed in June, 1999. A further data run is planned. Preliminary results from the four completed data-taking runs will be presented and discussed.