= SNO solar-neutrino flavor experiment
{c}
{title2=2001–2002}
In 2001, $240.95$ live days, reconstructed radius below $5.50\,\mathrm m$ and effective <Electron> kinetic <energy> above $6.75\,\mathrm{MeV}$ gave a CC <neutrino flux> of $1.75\times10^6\,\mathrm{cm}^{-2}\mathrm{s}^{-1}$ for the assumed <boron>-8 spectrum. Source calibrations measured $1.4\%$ instrumental-cut signal loss. SNO's own CC–ES difference was $1.6\sigma$; comparison with <Super-Kamiokande>'s precise ES flux gave $3.3\sigma$ evidence for non-electron active <neutrinos>. This was not an NC measurement.<Measurement of the Rate of νe + d → p + p + e− Interactions Produced by 8B Solar Neutrinos at the Sudbury Neutrino Observatory by Q. R. Ahmad and others>[PDF pp. 2–5: cuts, calibration and CC–ES inference; central flux]{ref}
In 2002 the pure-<heavy water> analysis used $306.4$ live days and a $5\,\mathrm{MeV}$ reconstructed kinetic-<energy> threshold. NC <neutrons> captured on <deuterons> emitted $6.25\,\mathrm{MeV}$ <gamma rays>, producing secondary <Electron> light. The NC reaction threshold was $2.2\,\mathrm{MeV}$, a different quantity. <Californium>-252 calibrated $29.9\%$ capture efficiency, but only $14.4\%$ detection efficiency after fiducial and <energy> cuts. Assays constrained backgrounds from <radioactive decay> and photodisintegration.<Direct Evidence for Neutrino Flavor Transformation from Neutral-Current Interactions in the Sudbury Neutrino Observatory by Q. R. Ahmad and others>[PDF pp. 2–3: neutron calibration, thresholds and backgrounds]{ref}
Energy, radius and direction relative to the <Sun> statistically separated channels. Assuming the standard <boron>-8 spectral shape, the NC total active <neutrino flux> was $5.09^{+0.44}_{-0.43}\,\mathrm{(stat.)}^{+0.46}_{-0.43}\,\mathrm{(syst.)}\times10^6\,\mathrm{cm}^{-2}\mathrm{s}^{-1}$, consistent with <stellar structure> predictions. The non-electron active component differed from zero by $5.3\sigma$. This established active flavour conversion, without individually tagging <muon neutrinos> and <tau neutrinos>. It did not exclude every sterile admixture.<Direct Evidence for Neutrino Flavor Transformation from Neutral-Current Interactions in the Sudbury Neutrino Observatory by Q. R. Ahmad and others>[PDF pp. 4–5, Fig. 3: constrained-spectrum fluxes and non-electron component]{ref}
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