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The report of a measurement of solar neutrinos through their neutral
current interactions with deuterium in the Sudbury Neutrino Observatory
represents the realization of an idea of the late Professor Herb
Chen for an experiment which would directly
resolve the solar neutrino problem.
Please come see a picture of our happy group, or take a look at some other Quicktime movies and photos of the SNO detector. Or feel free to see Bob Stokstad's pictorial tour of the Sudbury Neutrino Observatory. If you would like to get more infomation about the Sudbury Neutrino Observatory, you may try the official collaboration site or browse through our older web pages. SNO publications list is available here.
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| Direct Evidence for Neutrino Flavor Transformation from Neutral-Current Interactions in the Sudbury Neutrino Observatory (postscript) (pdf) 20 April 2002 |
| Observations of neutral-current neutrino interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral-current, elastic scattering, and charged-current reactions and assuming the standard 8B shape, the electron neutrino component of the 8B solar flux is 1.76+0.05-0.05(stat.)+0.09-0.09(sys.)x106cm-2s-1 for a kinetic energy threshold of 5 MeV. The non-electron neutrino component is 3.41+0.45-0.45(stat.)+0.48-0.45(sys.)x106cm-2s-1, 5.3 sigma greater than zero, providing strong evidence for solar electron neutrino flavor transformtion. The total flux measured with the NC reaction is 5.09+0.44-0.43(stat.)+0.46-0.43(sys.)x106cm-2s-1, consistent with standard models. |
| Measurement of Day and Night Neutrino Energy Spectra at SNO and Constraints on Neutrino Mixing Parameters (postscript) (pdf) 20 April 2002 |
| The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged-current events, assuming an undistorted 8B spectrum, the night minus day rate is 14.0%+/-6.3%+1.51.4% of the average rate. If the total flux of active neutrinos is constrained to have no asymmetry, the electron neutrino asymmetry is found to be 7.0%+/-4.9%+1.31.2%. A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the Large Mixing Angle (LMA) solution. |
| Measurement of the Rate of ne + d --> p + p + e- Interactions Produced by 8B Solar Neutrinos at the Sudbury Neutrino Observatory (Q.R. Ahmad et al. Phys. Rev. Lett., 87, 071301 (2001), nucl-ex/0106015) |
| Solar neutrinos from 8B 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 ne's is measured by the CC reaction rate to be fCC(ne)=1.75+/-0.07(stat.)+0.12-0.11(syst.)+/-0.05(theor.)x106cm-2s-1. Comparisons of fCC(ne) to the Super-Kamiokande Collaboration's precision value of the flux inferred from the ES reaction yields a 3.3s difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non-ne component in the solar flux. The total flux of active 8B neutrinos is determined to be 5.44+/-0.99x106cm-2s-1. |
| The Sudbury Neutrino Observatory (The SNO Collaboration, J. Boger et al., Nucl. Instr. Meth. A449, 172 (2000), nucl-ex/9910016) |
| The Sudbury Neutrino Observatory is a second generation water Cherenkov detector designed to determne whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The detector is unique in its use of D2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison o fthe charded- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Obsrvatory are described. Data and predicted operating parameters are provided whenever possible. |
