12,861 research outputs found

    Solar neutrino measurements using the full data period of Super-Kamiokande-IV

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    International audienceAn analysis of solar neutrino data from the fourth phase of Super-Kamiokande~(SK-IV) from October 2008 to May 2018 is performed and the results are presented. The observation time of the data set of SK-IV corresponds to 29702970~days and the total live time for all four phases is 58055805~days. For more precise solar neutrino measurements, several improvements are applied in this analysis: lowering the data acquisition threshold in May 2015, further reduction of the spallation background using neutron clustering events, precise energy reconstruction considering the time variation of the PMT gain. The observed number of solar neutrino events in 3.493.49--19.4919.49~MeV electron kinetic energy region during SK-IV is 65,443388+390(stat.)±925(syst.)65,443^{+390}_{-388}\,(\mathrm{stat.})\pm 925\,(\mathrm{syst.}) events. Corresponding 8B\mathrm{^{8}B} solar neutrino flux is (2.314±0.014(stat.)±0.040(syst.))×106 cm2s1(2.314 \pm 0.014\, \rm{(stat.)} \pm 0.040 \, \rm{(syst.)}) \times 10^{6}~\mathrm{cm^{-2}\,s^{-1}}, assuming a pure electron-neutrino flavor component without neutrino oscillations. The flux combined with all SK phases up to SK-IV is (2.336±0.011(stat.)±0.043(syst.))×106 cm2s1(2.336 \pm 0.011\, \rm{(stat.)} \pm 0.043 \, \rm{(syst.)}) \times 10^{6}~\mathrm{cm^{-2}\,s^{-1}}. Based on the neutrino oscillation analysis from all solar experiments, including the SK 58055805~days data set, the best-fit neutrino oscillation parameters are sin2θ12,solar=0.306±0.013\rm{sin^{2} \theta_{12,\,solar}} = 0.306 \pm 0.013 and Δm21,solar2=(6.100.81+0.95)×105 eV2\Delta m^{2}_{21,\,\mathrm{solar}} = (6.10^{+ 0.95}_{-0.81}) \times 10^{-5}~\rm{eV}^{2}, with a deviation of about 1.5σ\sigma from the Δm212\Delta m^{2}_{21} parameter obtained by KamLAND. The best-fit neutrino oscillation parameters obtained from all solar experiments and KamLAND are sin2θ12,global=0.307±0.012\sin^{2} \theta_{12,\,\mathrm{global}} = 0.307 \pm 0.012 and Δm21,global2=(7.500.18+0.19)×105 eV2\Delta m^{2}_{21,\,\mathrm{global}} = (7.50^{+ 0.19}_{-0.18}) \times 10^{-5}~\rm{eV}^{2}

    Solar neutrino measurements using the full data period of Super-Kamiokande-IV

    No full text
    International audienceAn analysis of solar neutrino data from the fourth phase of Super-Kamiokande~(SK-IV) from October 2008 to May 2018 is performed and the results are presented. The observation time of the data set of SK-IV corresponds to 29702970~days and the total live time for all four phases is 58055805~days. For more precise solar neutrino measurements, several improvements are applied in this analysis: lowering the data acquisition threshold in May 2015, further reduction of the spallation background using neutron clustering events, precise energy reconstruction considering the time variation of the PMT gain. The observed number of solar neutrino events in 3.493.49--19.4919.49~MeV electron kinetic energy region during SK-IV is 65,443388+390(stat.)±925(syst.)65,443^{+390}_{-388}\,(\mathrm{stat.})\pm 925\,(\mathrm{syst.}) events. Corresponding 8B\mathrm{^{8}B} solar neutrino flux is (2.314±0.014(stat.)±0.040(syst.))×106 cm2s1(2.314 \pm 0.014\, \rm{(stat.)} \pm 0.040 \, \rm{(syst.)}) \times 10^{6}~\mathrm{cm^{-2}\,s^{-1}}, assuming a pure electron-neutrino flavor component without neutrino oscillations. The flux combined with all SK phases up to SK-IV is (2.336±0.011(stat.)±0.043(syst.))×106 cm2s1(2.336 \pm 0.011\, \rm{(stat.)} \pm 0.043 \, \rm{(syst.)}) \times 10^{6}~\mathrm{cm^{-2}\,s^{-1}}. Based on the neutrino oscillation analysis from all solar experiments, including the SK 58055805~days data set, the best-fit neutrino oscillation parameters are sin2θ12,solar=0.306±0.013\rm{sin^{2} \theta_{12,\,solar}} = 0.306 \pm 0.013 and Δm21,solar2=(6.100.81+0.95)×105 eV2\Delta m^{2}_{21,\,\mathrm{solar}} = (6.10^{+ 0.95}_{-0.81}) \times 10^{-5}~\rm{eV}^{2}, with a deviation of about 1.5σ\sigma from the Δm212\Delta m^{2}_{21} parameter obtained by KamLAND. The best-fit neutrino oscillation parameters obtained from all solar experiments and KamLAND are sin2θ12,global=0.307±0.012\sin^{2} \theta_{12,\,\mathrm{global}} = 0.307 \pm 0.012 and Δm21,global2=(7.500.18+0.19)×105 eV2\Delta m^{2}_{21,\,\mathrm{global}} = (7.50^{+ 0.19}_{-0.18}) \times 10^{-5}~\rm{eV}^{2}

    Gamow-Teller decay of <math><mmultiscripts><mi>Te</mi><mprescripts/><none/><mn>142</mn></mmultiscripts></math> to <math><mmultiscripts><mi mathvariant="normal">I</mi><mprescripts/><none/><mn>142</mn></mmultiscripts></math>

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    International audienceThe β decay of Te90142 to I89142 was investigated for the first time. The parent nucleus was produced by the in-flight fission of a U238 beam with an energy of 345 MeV per nucleon, impinging on a Be9 target at the Radioactive Isotope Beam Factory of RIKEN. Excited states in I142 were established by β-delayed γ-ray spectroscopy. The observed (1+) states in I142 could be interpreted to be predominantly the ν0h9/2⊗π0h11/2 configuration formed by a Gamow-Teller transition between a neutron in the 0h9/2 orbital and a proton in the 0h11/2 orbital. Additional features of the (1+) states are discussed by comparing with neighboring heavier isotones, such as Cs144 and La146. In the context of deformed shell-model calculations, the (11+) state is closely related to the ν[5,3,2]3/2⊗π[5,5,0]1/2 configuration, which may be related to the weak Gamow-Teller transition strength

    Search for Eccentric Black Hole Coalescences during the Third Observing Run of LIGO and Virgo

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    Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70M>70 MM_\odot) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e0.30 < e \leq 0.3 at 0.330.33 Gpc3^{-3} yr1^{-1} at 90\% confidence level.Comment: 24 pages, 5 figure

    Updated T2K measurements of muon neutrino and antineutrino disappearance using 3.6 ×\times 1021^{21} protons on target

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    International audienceMuon neutrino and antineutrino disappearance probabilities are identical in the standard three-flavor neutrino oscillation framework, but CPT violation and non-standard interactions can violate this symmetry. In this work we report the measurements of sin2θ23\sin^{2} \theta_{23} and Δm322\Delta m_{32}^2 independently for neutrinos and antineutrinos. The aforementioned symmetry violation would manifest as an inconsistency in the neutrino and antineutrino oscillation parameters. The analysis discussed here uses a total of 1.97×\times1021^{21} and 1.63×\times1021^{21} protons on target taken with a neutrino and antineutrino beam respectively, and benefits from improved flux and cross-section models, new near detector samples and more than double the data reducing the overall uncertainty of the result. No significant deviation is observed, consistent with the standard neutrino oscillation picture

    Gamow-Teller decay of <math><mmultiscripts><mi>Te</mi><mprescripts/><none/><mn>142</mn></mmultiscripts></math> to <math><mmultiscripts><mi mathvariant="normal">I</mi><mprescripts/><none/><mn>142</mn></mmultiscripts></math>

    No full text
    International audienceThe β decay of Te90142 to I89142 was investigated for the first time. The parent nucleus was produced by the in-flight fission of a U238 beam with an energy of 345 MeV per nucleon, impinging on a Be9 target at the Radioactive Isotope Beam Factory of RIKEN. Excited states in I142 were established by β-delayed γ-ray spectroscopy. The observed (1+) states in I142 could be interpreted to be predominantly the ν0h9/2⊗π0h11/2 configuration formed by a Gamow-Teller transition between a neutron in the 0h9/2 orbital and a proton in the 0h11/2 orbital. Additional features of the (1+) states are discussed by comparing with neighboring heavier isotones, such as Cs144 and La146. In the context of deformed shell-model calculations, the (11+) state is closely related to the ν[5,3,2]3/2⊗π[5,5,0]1/2 configuration, which may be related to the weak Gamow-Teller transition strength

    Search for subsolar-mass black hole binaries in the second part of Advanced LIGO's and Advanced Virgo's third observing run