The SNO+ Collaboration reports the first evidence of reactor antineutrinos in a Cherenkov detector. The nearest nuclear reactors are located 240 km away in Ontario, Canada. This analysis uses events ...with energies lower than in any previous analysis with a large water Cherenkov detector. Two analytical methods are used to distinguish reactor antineutrinos from background events in 190 days of data and yield consistent evidence for antineutrinos with a combined significance of 3.5σ.
Here, a measurement of the 8B solar neutrino flux has been made using a 69.2 kt-day dataset acquired with the SNO+ detector during its water commissioning phase. At energies above 6 MeV the dataset ...is an extremely pure sample of solar neutrino elastic scattering events, owing primarily to the detector’s deep location, allowing an accurate measurement with relatively little exposure. In that energy region the best fit background rate is 0.25+0.09–0.07 events/kt–day, significantly lower than the measured solar neutrino event rate in that energy range, which is 1.03+0.13–0.12 events/kt–day. Also using data below this threshold, down to 5 MeV, fits of the solar neutrino event direction yielded an observed flux of 2.53+0.31–0.28(stat)+0.13–0.10(syst) × 106 cm–2 s–1, assuming no neutrino oscillations. This rate is consistent with matter enhanced neutrino oscillations and measurements from other experiments.
At the close of the Fourth International Polar Year, we take stock of the ecological consequences of recent climate change in the Arctic, focusing on effects at population, community, and ecosystem ...scales. Despite the buffering effect of landscape heterogeneity, Arctic ecosystems and the trophic relationships that structure them have been severely perturbed. These rapid changes may be a bellwether of changes to come at lower latitudes and have the potential to affect ecosystem services related to natural resources, food production, climate regulation, and cultural integrity. We highlight areas of ecological research that deserve priority as the Arctic continues to warm.
The direction of individual
B
8
solar neutrinos has been reconstructed using the
SNO
+
liquid scintillator detector. Prompt, directional Cherenkov light was separated from the slower, isotropic ...scintillation light using time information, and a maximum likelihood method was used to reconstruct the direction of individual scattered electrons. A clear directional signal was observed, correlated with the solar angle. The observation was aided by a period of low primary fluor concentration that resulted in a slower scintillator decay time. This is the first time that event-by-event direction reconstruction in high light-yield liquid scintillator has been demonstrated in a large-scale detector.
Published by the American Physical Society
2024
Surgical injury to the pancreas is thought to occur commonly during procurement. The UK Transplant Registry was analyzed to determine the frequency of pancreatic injuries, identify factors associated ...with damage, and assess the impact of injuries on graft survival. Twelve hundred ninety‐six pancreata were procured from donation after brain death donors, with 314 (19.5%) from donation after circulatory death donors. More than 50% of recovered pancreata had at least one injury, most commonly a short portal vein (21.5%). Liver donation, procurement team origin, hepatic artery (HA) arising from the superior mesenteric artery (SMA), and increasing donor BMI were associated with increased rates of pancreas damage on univariate analyses; on multivariate analysis only the presence of an HA from the SMA remained significant (p = 0.02). Six hundred forty solid organ pancreas transplants were performed; 238 had some form of damage. Overall, there was no difference in graft survival between damaged and undamaged organs (p = 0.28); however, graft loss was significantly more frequent in pancreata with arterial damage (p = 0.04) and in those with parenchymal damage (p = 0.05). Damage to the pancreas during organ recovery is more common than other organs, and meticulous surgical technique and awareness of damage risk factors are essential to reduce rates of procurement‐related injuries.
The authors describe a UK registry analysis of surgical injuries to the pancreas during procurement, identify that damage occurs more frequently than in other abdominal solid organs, and find that the presence of a donor accessory right hepatic artery is independently associated with an increased risk of pancreatic injury. See also the editorial from Knechtle and Sudan on page 2791 and the article from Heylen et al on page 2900.
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.
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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