Solar neutrinos from (8)B decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of nu(e)'s is measured by the CC reaction rate to be straight phi(CC)(nu(e)) = 1.75 +/- 0.07(stat)(+0.12)(-0.11)(syst) +/- 0.05(theor) x 10(6) cm(-2) s(-1). Comparison of straight phi(CC)(nu(e)) to the Super-Kamiokande Collaboration's precision value of the flux inferred from the ES reaction yields a 3.3 sigma difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non- nu(e) component in the solar flux. The total flux of active 8B neutrinos is determined to be 5.44+/-0.99 x 10(6) cm(-2) s(-1).
The circular polarization of the 1.081 MeV y rays from "F has been measured to be (1.7+5.8)X10 . "F was produced by a 4.05 MeV He+ beam impinging on a recirculating water target with a thin entrance window. The circular polarization was measured with four magnetic transmission polarimeters, each backed by a 150 cm' n-type Cxe detector. A fast data acquisition system limited overall peak losses to 30% at a count rate of 60 kHz per detector. Supplementary experiments were carried out to investigate the sensitivity of the circular polarization measurement to systematic variations of beam position and intensity. These effects were found to be negligible relative to the statistical uncertainty. The experimental result is interpreted in terms of an isovector parity-nonconserving matrix element between the~0+, T = 1, 1.042 MeV ) and 0,T =0, 1.081 MeV) states in ' F that is dominated by the weak pion exchange contribution.The present result for the weak pion-nucleon coupling strength is~f'~=(0.4+O4)&& 10 ', which is significantly smaller than recent theoretical predictions based on the Weinberg-Salam model.'Present address:
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