The Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory is a second generation water Cherenkov detector designed to determine 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 of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.Comment: 58 pages, 12 figures, submitted to Nucl. Inst. Meth. Uses elsart and epsf style files. For additional information about SNO see http://www.sno.phy.queensu.ca . This version has some new reference

Measurement of the νe and total 8B solar neutrino fluxes with the Sudbury Neutrino Observatory phase-III data set

This paper details the solar neutrino analysis of the 385.17-day phase-III data set acquired by the Sudbury Neutrino Observatory (SNO). An array of 3He proportional counters was installed in the heavy-water target to measure precisely the rate of neutrino-deuteron neutral-current interactions. This technique to determine the total active 8B solar neutrino flux was largely independent of the methods employed in previous phases. The total flux of active neutrinos was measured to be 5.54-0.31+0.33(stat.)-0.34+0.36(syst.)×106 cm-2 s-1, consistent with previous measurements and standard solar models. A global analysis of solar and reactor neutrino mixing parameters yielded the best-fit values of Δm2=7.59-0.21+0.19×10 -5eV2 and θ=34.4-1.2+1.3degrees

First neutrino observations from the sudbury neutrino observatory

The first neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by 8B solar neutrinos, detected by the charged current reaction on deuterium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Quantitative results for the fluxes observed with these reactions will be provided when further calibrations have been completed

Electron energy spectra, fluxes, and day-night asymmetries of boron-8 solar neutrinos from the 391-day salt phase sno data set

Results are reported from the complete salt phase of the Sudbury Neutrino Observatory experiment in which NaCl was dissolved in the D_2O target. The addition of salt enhanced the signal from neutron capture, as compared to the pure D_2O detector. By making a statistical separation of charged-current events from other types based on event-isotropy criteria, the effective electron recoil energy spectrum has been extracted. In units of 106 cm-2 s-1, the total flux of active-flavor neutrinos from 8B decay in the Sun is found to be 4.94+0.21_-0.21(stat)+0.38_-0.34(syst) and the integral flux of electron neutrinos for an undistorted 8B spectrum is 1.68+0.06_-0.06(stat)+0.08_-0.09(syst); the signal from (nu_x,e) elastic scattering is equivalent to an electron-neutrino flux of 2.35+0.22-0.22(stat)+0.15_-0.15(syst). These results are consistent with those expected for neutrino oscillations with the so-called Large Mixing Angle parameters, and also with an undistorted spectrum. A search for matter-enhancement effects in the Earth through a possible day-night asymmetry in the charged-current integral rate is consistent with no asymmetry. Including results from other experiments, the best-fit values for two-neutrino mixing parameters are Delta m2 = (8.0+0.6_-0.4) x 10-5 eV2 and theta = 33.9 +2.4_-2.2 degrees

Measurement of CC interactions produced by8B solar neutrinos at SNO

The Sudbury Neutrino Observatory (SNO) is a 1000 tonne heavy water Cherenkov detector placed 2 km underground in Ontario, Canada. Its main purpose is the detection of solar neutrinos, but it is also sensitive to atmospheric and supernova neutrinos. In this paper we report our first measurement of the solar electron-type neutrino flux using the charged current interaction on deuterium, above an electron kinetic energy threshold of 6.75 MeV. This measurement, when compared with an electron scattering measurement from Super Kamiokande, provides the first evidence for non-electron neutrino types from the Sun implying flavor change of solar electron neutrinos. We also present an initial angular distribution of through-going muons, which shows that we can detect neutrino-induced muons from well above the horizontal. This will give us good sensitivity to neutrino oscillations in the atmospheric sector

Neutral current and day night measurements from the pure D2O phase of SNO

The Sudbury Neutrino Observatory is a 1000 T D2O Cerenkov detector that is sensitive to 8B solar neutrinos. The energy, radius, and direction with respect to the sun is measured for each neutrino event; these distributions are used to separately determine the rates of the charged current, neutral current and electron scattering reactions of neutrinos on deuterium. Assuming an undistorted 8B spectrum, the νe component of the 8B solar flux is φe = 1.76-0.05 +0.05 (stat. -0.09 +0.09 (syst.) × 106 cm-2s-1 based on events with a measured kinetic energy above 5 MeV. The non-νe component is φμτ = 3.41-0.45 +0.45 (stat. -0.45 +0.48 (syst.) × 106 cm-2s-1, 5.3σ greater than zero, providing strong evidence for solar νe flavor transformation. The total flux measured with the NC reaction is φNC = 5.09-0.43 +0.44(stat. -0.43 +0.46 (syst.) × 106 cm-2s-1, consistent with solar models. The night minus day rate is 14.0% ± 6.3%-1.4 +1.5% of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the νe asymmetry is found to be 7.0% ± 4.9%-1.2 +1.3%. A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the Large Mixing Angle (LMA) solution