A Search for Neutrinos from the Solar hep Reaction and the Diffuse Supernova Neutrino Background with the Sudbury Neutrino Observatory

A search has been made for neutrinos from the hep reaction in the Sun and from the diffus

Measurement of the Total Active 8B Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity

The Sudbury Neutrino Observatory (SNO) has precisely determined the total active (nu_x) 8B solar neutrino flux without assumptions about the energy dependence of the nu_e survival probability. The measurements were made with dissolved NaCl in the heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21 +/- 0.27 (stat) +/- 0.38 (syst) x10^6 cm^{-2}s^{-1}, in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Delta m^{2} = 7.1^{+1.2}_{-0.6}x10^{-5} ev^2 and theta = 32.5^{+2.4}_{-2.3} degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.Comment: Submitted to Phys. Rev. Let

Electron Antineutrino Search at the Sudbury Neutrino Observatory

Upper limits on the \nuebar flux at the Sudbury Neutrino Observatory have been set based on the \nuebar charged-current reaction on deuterium. The reaction produces a positron and two neutrons in coincidence. This distinctive signature allows a search with very low background for \nuebar's from the Sun and other potential sources. Both differential and integral limits on the \nuebar flux have been placed in the energy range from 4 -- 14.8 MeV. For an energy-independent \nu_e --> \nuebar conversion mechanism, the integral limit on the flux of solar \nuebar's in the energy range from 4 -- 14.8 MeV is found to be \Phi_\nuebar <= 3.4 x 10^4 cm^{-2} s^{-1} (90% C.L.), which corresponds to 0.81% of the standard solar model 8B \nu_e flux of 5.05 x 10^6 cm^{-2} s^{-1}, and is consistent with the more sensitive limit from KamLAND in the 8.3 -- 14.8 MeV range of 3.7 x 10^2 cm^{-2} s^{-1} (90% C.L.). In the energy range from 4 -- 8 MeV, a search for \nuebar's is conducted using coincidences in which only the two neutrons are detected. Assuming a \nuebar spectrum for the neutron induced fission of naturally occurring elements, a flux limit of Phi_\nuebar <= 2.0 x 10^6 cm^{-2} s^{-1}(90% C.L.) is obtained.Comment: submitted to Phys. Rev.

Measurement of the rate of nu_e + d --> p + p + e^- interactions produced by 8B solar neutrinos at the Sudbury Neutrino Observatory

Solar neutrinos from the decay of $^8$B have been detected at the Sudbury Neutrino Observatory (SNO) via the charged current (CC) reaction on deuterium and by the elastic scattering (ES) of electrons. The CC reaction is sensitive exclusively to nu_e's, while the ES reaction also has a small sensitivity to nu_mu's and nu_tau's. The flux of nu_e's from ^8B decay measured by the CC reaction rate is \phi^CC(nu_e) = 1.75 +/- 0.07 (stat)+0.12/-0.11 (sys.) +/- 0.05(theor) x 10^6 /cm^2 s. Assuming no flavor transformation, the flux inferred from the ES reaction rate is \phi^ES(nu_x) = 2.39+/-0.34 (stat.)+0.16}/-0.14 (sys) x 10^6 /cm^2 s. Comparison of \phi^CC(nu_e) to the Super-Kamiokande Collaboration's precision value of \phi^ES(\nu_x) yields a 3.3 sigma difference, providing evidence that there is a non-electron flavor active neutrino component in the solar flux. The total flux of active ^8B neutrinos is thus determined to be 5.44 +/-0.99 x 10^6/cm^2 s, in close agreement with the predictions of solar models.Comment: 6 pages (LaTex), 3 figures, submitted to Phys. Rev. Letter

Garden and landscape-scale correlates of moths of differing conservation status: significant effects of urbanization and habitat diversity

Moths are abundant and ubiquitous in vegetated terrestrial environments and are pollinators, important herbivores of wild plants, and food for birds, bats and rodents. In recent years, many once abundant and widespread species have shown sharp declines that have been cited by some as indicative of a widespread insect biodiversity crisis. Likely causes of these declines include agricultural intensification, light pollution, climate change, and urbanization; however, the real underlying cause(s) is still open to conjecture. We used data collected from the citizen science Garden Moth Scheme (GMS) to explore the spatial association between the abundance of 195 widespread British species of moth, and garden habitat and landscape features, to see if spatial habitat and landscape associations varied for species of differing conservation status. We found that associations with habitat and landscape composition were species-specific, but that there were consistent trends in species richness and total moth abundance. Gardens with more diverse and extensive microhabitats were associated with higher species richness and moth abundance; gardens near to the coast were associated with higher richness and moth abundance; and gardens in more urbanized locations were associated with lower species richness and moth abundance. The same trends were also found for species classified as increasing, declining and vulnerable under IUCN (World Conservation Union) criteria

Combined Analysis of all Three Phases of Solar Neutrino Data from the Sudbury Neutrino Observatory

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 \pm 0.16(stat.)+0.11-0.13(syst.))\times10^6 cm^{-2}s^{-1}. A two-flavor neutrino oscillation analysis yielded \Deltam^2_{21} = (5.6^{+1.9}_{-1.4})\times10^{-5} eV^2 and tan^2{\theta}_{12}= 0.427^{+0.033}_{-0.029}. A three-flavor neutrino oscillation analysis combining this result with results of all other solar neutrino experiments and the KamLAND experiment yielded \Deltam^2_{21} = (7.41^{+0.21}_{-0.19})\times10^{-5} eV^2, tan^2{\theta}_{12} = 0.446^{+0.030}_{-0.029}, and sin^2{\theta}_{13} = (2.5^{+1.8}_{-1.5})\times10^{-2}. This implied an upper bound of sin^2{\theta}_{13} < 0.053 at the 95% confidence level (C.L.)

Low Multiplicity Burst Search at the Sudbury Neutrino Observatory

Results are reported from a search for low-multiplicity neutrino bursts in the Sudbury Neutrino Observatory (SNO). Such bursts could indicate detection of a nearby core-collapse supernova explosion. The data were taken from Phase I (November 1999 - May 2001), when the detector was filled with heavy water, and Phase II (July 2001 - August 2003), when NaCl was added to the target. The search was a blind analysis in which the potential backgrounds were estimated and analysis cuts were developed to eliminate such backgrounds with 90% confidence before the data were examined. The search maintained a greater than 50% detection probability for standard supernovae occurring at a distance of up to 60 kpc for Phase I and up to 70 kpc for Phase II. No low-multiplicity bursts were observed during the data-taking period.Comment: 11 pages, 4 figures, submitted to Ap

Independent measurement of the total active B8 solar neutrino flux using an array of He3 proportional counters at the Sudbury Neutrino Observatory

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 (νx) 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)×106  cm-2 s-1, in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields Δm2=7.59-0.21+0.19×10-5  eV2 and θ=34.4-1.2+1.3 degrees. The uncertainty on the mixing angle has been reduced from SNO’s previous results

Low-Multiplicity Burst Search At The Sudbury Neutrino Observatory

Results are reported from a search for low-multiplicity neutrino bursts in the Sudbury Neutrino Observatory. Such bursts could indicate the detection of a nearby core-collapse supernova explosion. The data were taken from Phase I (1999 November-2001 May), when the detector was filled with heavy water, and Phase II (2001 July-2003 August), when NaCl was added to the target. The search was a blind analysis in which the potential backgrounds were estimated and analysis cuts were developed to eliminate such backgrounds with 90% confidence before the data were examined. The search maintained a greater than 50% detection probability for standard supernovae occurring at a distance of up to 60 kpc for Phase I and up to 70 kpc for Phase II. No low-multiplicity bursts were observed during the data-taking period.Natural Sciences and Engineering Research Council, CanadaIndustry Canada, CanadaNational Research Council, CanadaNorthern Ontario Heritage Fund, CanadaAtomic Energy of Canada, Ltd., CanadaOntario Power Generation, CanadaHigh Performance Computing Virtual Laboratory, CanadaCanada Foundation for Innovation, CanadaCanada Research Chairs, CanadaDepartment of Energy, USNational Energy Research Scientific Computing Center, USAlfred P. Sloan Foundation, USScience and Technology Facilities Council, UKFundacao para a Ciencia e a Technologia, PortugalAstronom