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.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Tests on B−L symmetry breaking models are important probes to search for new physics. One proposed model with Δ(B−L)=2 involves the oscillations of a neutron to an antineutron. In this paper, a new ...limit on this process is derived for the data acquired from all three operational phases of the Sudbury Neutrino Observatory experiment. The search concentrated on oscillations occurring within the deuteron, and 23 events were observed against a background expectation of 30.5 events. These translated to a lower limit on the nuclear lifetime of 1.48×1031 yr at 90% C.L. when no restriction was placed on the signal likelihood space (unbounded). Alternatively, a lower limit on the nuclear lifetime was found to be 1.18×1031 yr at 90% C.L. when the signal was forced into a positive likelihood space (bounded). Values for the free oscillation time derived from various models are also provided in this article. This is the first search for neutron-antineutron oscillation with the deuteron as a target.
Full text
Available for:
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.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The Sudbury Neutrino Observatory (SNO) used an array of {sup 3}He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active ...({nu}{sub x}) {sup 8}B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54{sub -0.31}{sup +0.33}(stat){sub -0.34}{sup +0.36}(syst)x10{sup 6} cm{sup -2} s{sup -1}, in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields {delta}m{sup 2}=7.59{sub -0.21}{sup +0.19}x10{sup -5} eV{sup 2} and {theta}=34.4{sub -1.2}{sup +1.3} degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Experimental tests of Lorentz symmetry in systems of all types are critical for ensuring that the basic assumptions of physics are well founded. Data from all phases of the Sudbury Neutrino ...Observatory, a kiloton-scale heavy water Cherenkov detector, are analyzed for possible violations of Lorentz symmetry in the neutrino sector. Such violations would appear as one of eight possible signal types in the detector: six seasonal variations in the solar electron neutrino survival probability differing in energy and time dependence and two shape changes to the oscillated solar neutrino energy spectrum. No evidence for such signals is observed, and limits on the size of such effects are established in the framework of the standard model extension, including 38 limits on previously unconstrained operators and improved limits on 16 additional operators. This makes limits on all minimal, Dirac-type Lorentz violating operators in the neutrino sector available for the first time.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The Sudbury Neutrino Observatory (SNO) used an array of 3He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active (nu_x) ...8B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54_-0.31;+0.33(stat)-0.34+0.36(syst)x10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields Deltam2=7.59_-0.21;+0.19x10(-5) eV2 and theta=34.4_-1.2;+1.3 degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Neutrons produced in nuclear interactions initiated by cosmic-ray muons present an irreducible background to many rare-event searches, even in detectors located deep underground. Models for the ...production of these neutrons have been tested against previous experimental data, but the extrapolation to deeper sites is not well understood. Here we report results from an analysis of cosmogenically produced neutrons at the Sudbury Neutrino Observatory. A specific set of observables are presented, which can be used to benchmark the validity of geant4 physics models. In addition, the cosmogenic neutron yield, in units of 10−4 cm2/(g·μ), is measured to be 7.28±0.09(stat)−1.12+1.59(syst) in pure heavy water and 7.30±0.07(stat)−1.02+1.40(syst) in NaCl-loaded heavy water. These results provide unique insights into this potential background source for experiments at SNOLAB.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The (nat)Pb(3He,tp) reaction at E(3He) = 177 MeV was studied to identify 2Planck's over 2piomega isovector monopole strength in Bi isotopes. Monopole strength was found in the region -45<Q<-30 MeV in ...the coincidence data. The cross section is compared with distorted-wave Born approximation calculations for non-spin-flip and spin-flip isovector monopole resonances. The observed spin-flip and non-spin-flip monopole strengths in the proton-decay channel amount to 20% of the respective non-energy-weighted sum rule.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
10.
SNEWS: the SuperNova Early Warning System Antonioli, Pietro; Fienberg, Richard Tresch; Fleurot, Fabrice ...
New journal of physics,
09/2004, Volume:
6
Journal Article
PDF
