Final results from SNO Tolich, N
Journal of physics. Conference series,
07/2012, Volume:
375, Issue:
4
Journal Article, Conference Proceeding
Peer reviewed
Open access
We report results from a combined analysis of solar neutrino data from all phases of the Sudbury Neutrino Observatory. By exploiting particle identification information obtained from the proportional ...counters installed during the third phase, this analysis improved background rejection in that phase of the experiment. The combined analysis resulted in a total flux of active neutrino flavors from 8B decays in the Sun of (5.25 ± 0.16(stat.)+0.11−0.13(syst.)) × 106cm−2s−1. A three-flavor neutrino oscillation analysis combining this result with results of all other solar neutrino experiments and the KamLAND experiment yielded Δm221 (7.4l+0.21−0.19) × l0−5eV2, tan2 θ12 0.446+0.030−0.029, and sin2 θ13 (2.5+1.8−1.5) × 10−2. This implied an upper bound of sin2 θ13 < 0.053 at the 95% confidence level (C.L.).
An experimental test of the electron energy scale linearities of SNO+ and EJ-301 scintillators was carried out using a Compton spectrometer with electrons in the energy range 0.09–3
MeV. The ...linearity of the apparatus was explicitly demonstrated. It was found that the response of both types of scintillators with respect to electrons becomes non-linear below
∼
0.4
MeV
. An explanation is given in terms of Cherenkov light absorption and re-emission by the scintillators.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Final results from SNO Tolich, N
Journal of physics. Conference series,
01/2012, Volume:
375
Journal Article
Peer reviewed
We report results from a combined analysis of solar neutrino data from all phases of the Sudbury Neutrino Observatory. By exploiting particle identification information obtained from the proportional ...counters installed during the third phase, this analysis improved background rejection in that phase of the experiment. The combined analysis resulted in a total flux of active neutrino flavors from super(8)B decays in the Sun of (5.25 + or - 0.16(stat.) super(+0.11) sub(-0.13)(syst.)) x 10 super(6)cm super(-2)s super(-1). A three-flavor neutrino oscillation analysis combining this result with results of all other solar neutrino experiments and the KamLAND experiment yielded Delta m super(2) sub(21) = (7.41 super(+0.21) sub(0.19)) x 10 super(-5) eV super(2), tan super(2) theta sub(12) = 0.446 super(+0.030) sub(-0.029) , and sin super(2) theta sub(13) = (2.5 super(+1.8) sub(-1.5)) x 10 super(-2). This implied an upper bound of sin super(2) theta sub(13) < 0.053 at the 95% confidence level (C.L.).
SNO+ is a large liquid scintillator-based experiment located 2 km underground at SNOLAB, Sudbury, Canada. It reuses the Sudbury Neutrino Observatory detector, consisting of a 12 m diameter acrylic ...vessel which will be filled with about 780 tonnes of ultra-pure liquid scintillator. Designed as a multipurpose neutrino experiment, the primary goal of SNO+ is a search for the neutrinoless double-beta decay (0νββ) of 130Te. In Phase I, the detector will be loaded with 0.3% natural tellurium, corresponding to nearly 800 kg of 130Te, with an expected effective Majorana neutrino mass sensitivity in the region of 55–133 meV, just above the inverted mass hierarchy. Recently, the possibility of deploying up to ten times more natural tellurium has been investigated, which would enable SNO+ to achieve sensitivity deep into the parameter space for the inverted neutrino mass hierarchy in the future. Additionally, SNO+ aims to measure reactor antineutrino oscillations, low energy solar neutrinos, and geoneutrinos, to be sensitive to supernova neutrinos, and to search for exotic physics. A first phase with the detector filled with water will begin soon, with the scintillator phase expected to start after a few months of water data taking. The 0νββ Phase I is foreseen for 2017.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The long baseline between Earth and the Sun makes solar neutrinos an excellent test beam for exploring possible neutrino decay. The signature of such decay would be an energy-dependent distortion of ...the traditional survival probability which can be fit for using well-developed and high-precision analysis methods. Here a model including neutrino decay is fit to all three phases of B8 solar neutrino data taken by the Sudbury Neutrino Observatory (SNO). This fit constrains the lifetime of neutrino mass state ν2 to be >8.08×10−5 s/eV at 90% confidence. An analysis combining this SNO result with those from other solar neutrino experiments results in a combined limit for the lifetime of mass state ν2 of >1.92×10−3 s/eV at 90% confidence.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
This paper reports results from a search for nucleon decay through invisible modes, where no visible energy is directly deposited during the decay itself, during the initial water phase of SNO+. ...However, such decays within the oxygen nucleus would produce an excited daughter that would subsequently deexcite, often emitting detectable gamma rays. A search for such gamma rays yields limits of 2.5×1029 y at 90% Bayesian credibility level (with a prior uniform in rate) for the partial lifetime of the neutron, and 3.6×1029 y for the partial lifetime of the proton, the latter a 70% improvement on the previous limit from SNO. We also present partial lifetime limits for invisible dinucleon modes of 1.3×1028 y for nn, 2.6×1028 y for pn and 4.7×1028 y for pp, an improvement over existing limits by close to 3 orders of magnitude for the latter two.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
A search has been performed for neutrinos from two sources, the hep reaction in the solar pp fusion chain and the νe component of the diffuse supernova neutrino background (DSNB), using the full ...dataset of the Sudbury Neutrino Observatory with a total exposure of 2.47 kton − years after fiducialization. The hep search is performed using both a single-bin counting analysis and a likelihood fit. We find a best-fit flux that is compatible with solar model predictions while remaining consistent with zero flux, and set a one-sided upper limit of Φhep < 30 × 103 cm−2 s−1 90% credible interval (CI). No events are observed in the DSNB search region, and we set an improved upper bound on the νe component of the DSNB flux of ΦνeDSNB < 19 cm−2 s−1 (90% CI) in the energy range 22.9 < Eν < 36.9 MeV.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
We study the effect of naval nuclear reactors on the study of neutrino oscillations. We find that the presence of naval reactors at unknown locations and times may limit the accuracy of future very ...long baseline reactor-based neutrino oscillation experiments. At the same time, we argue that a nuclear powered surface ship such as a large Russian icebreaker may provide an ideal source for precision experiments.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
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